Add shallowMerge function

[Gijsreyn]

PR Summary

This pull request adds the shallowMerge function, including its reference documentation. Also documented the tryWhich().

PR Context

Partially addresses #57.

[michaeltlombardi]

Suggested change

	the value from the last object in the array takes precedence.
	the value from the last object in the array with that property takes precedence.

[michaeltlombardi]

Suggested change

	This is a **shallow merge**, meaning:
	This is a _shallow merge_, which applies the following rules:

[michaeltlombardi]

Suggested change

	- Top-level properties are merged from all objects
	- If a property value is an object, it replaces the entire object from previous objects
	rather than merging the nested properties
	- Arrays and other complex types are also replaced entirely, not combined
	- The first object in the array defines the base value for the merged object.
	- The function processes each object in the array in the order they're defined.
	- When processing each object, the function iterates over every top-level property defined for that
	object and:
	- If the merged object doesn't already have the property, the function adds that property to the
	merged object with the value from the current object.
	- If the merged object does have the property, the function _replaces_ the existing value with
	the value from the current object, even when the value is an object or array.

[michaeltlombardi]

Suggested change

	- Building composite configuration objects from multiple sources
	- Applying configuration overrides where later values take precedence
	- Combining default settings with user-specified customizations
	- Merging environment-specific configurations
	- Building composite configuration objects from multiple sources.
	- Applying configuration overrides where later values take precedence.
	- Combining default settings with user-specified customizations.
	- Merging environment-specific configurations.

[michaeltlombardi]

Suggested change

	The shallow merge behavior differs from a deep merge (like [`union()`][00]) where nested
	objects would be recursively merged. With `shallowMerge()`, nested structures are replaced
	entirely by the last object's value.
	The shallow merge behavior differs from a deep merge (like [`union()`][00]) where nested
	objects are recursively merged. The `shallowMerge()` function replaces nested structures
	entirely with the value defined by the last object with that property in the input array.

[michaeltlombardi]

Suggested change

	This tries `python3` first, falls back to `python`, and finally uses a default path if
	neither is found in PATH.
	In this example, the function first looks for `python3` in the `PATH` environmental variable. If
	that executable isn't discovered, it then looks for `python`. If neither executable is discovered,
	it falls back to the specified default value, `/usr/bin/python3`.

[michaeltlombardi]

Suggested change

	allFound: "[and(not(equals(tryWhich('docker'), null())), not(equals(tryWhich('kubectl'), null())), not(equals(tryWhich('helm'), null())))]"
	allFound: >-
	[and(
	not(equals(tryWhich('docker'), null())),
	not(equals(tryWhich('kubectl'), null())),
	not(equals(tryWhich('helm'), null()))
	)]

[michaeltlombardi]

Suggested change

	The name of the executable to locate. On Windows, the function automatically checks for
	common executable extensions (.exe, .cmd, .bat, .ps1, etc.) if no extension is provided.
	The name of the executable to locate. On Windows, it automatically checks for common executable
	extensions, like `.exe, `.cmd`, and `.bat`, if no extension is provided.

[michaeltlombardi]

Suggested change

	The function returns `null` instead of generating errors when the executable is not found.
	It will return an error only if:
	- **Not a string**: The input is not a string (e.g., number, array, object, null)
	The function returns `null` instead of generating errors when the executable isn't found.
	The function only returns an error when the input isn't a string.

[michaeltlombardi]

Suggested change

	- The function searches the PATH environment variable in the same order as the operating system
	- On Windows, common executable extensions are automatically checked (.exe, .cmd, .bat, .ps1, etc.)
	- Returns `null` (not an error) when the executable is not found
	- The returned path is always absolute
	- Use with [`if()`][00] or [`coalesce()`][01] for conditional logic based on tool availability
	- The search is case-insensitive on Windows and case-sensitive on Unix-like systems
	- Symbolic links are resolved to their target paths
	- The function searches the `PATH` environment variable in the same order as the operating system.
	- On Windows, the function automatically checks for the executable with common extensions, like
	`.exe`, `.cmd`, and `.bat`, when the input string doesn't define an extension. For example, if
	the input is `dsc`, the function would return `dsc.exe` if available in `PATH`.
	- The function returns `null` when the executable isn't found instead of raising an error.
	- The function always returns the absolute path to a discovered executable.
	- Use with [`if()`][00] or [`coalesce()`][01] for conditional logic based on tool availability.
	- The function searches for the executable case-insensitively on Windows and case-sensitively on
	other platforms.
	- The function resolves symbolic links to their target paths.