feat(pds-dropdown-menu-item): add http-method and data attribute support

[pixelflips]

Problem

When using pds-dropdown for action columns in consuming applications (e.g., Rails DataTableComponent), developers need to support features like method: :delete, remote: true, and custom data attributes for confirmations and modals. Currently, this requires using raw link_to helpers which generate <a> tags directly in the dropdown menu.

This triggers console errors because pds-dropdown-menu strictly validates its children and only accepts pds-dropdown-menu-item and pds-dropdown-menu-separator elements:

Uncaught Error: pds-dropdown-menu only accepts pds-dropdown-menu-item and pds-dropdown-menu-separator elements

Additionally, due to Shadow DOM encapsulation, external JavaScript frameworks cannot intercept click events on elements inside the shadow root, making it impossible for framework-specific handlers to process non-GET requests.

Solution

Enhance pds-dropdown-menu-item to natively support HTTP methods and framework data attributes, allowing consuming applications to use the proper component instead of raw <a> tags.

New Props:

• http-method: Specifies HTTP method (get, post, put, patch, delete) - handles form submission internally with CSRF token
• turbo-frame: Sets target frame for SPA navigation
• turbo: Controls SPA-style navigation behavior (boolean)

New Event:

• pdsBeforeSubmit: Cancellable event emitted before form submission for non-GET methods, allowing custom handling (e.g., confirmation dialogs)

This is fully backward compatible - existing implementations are unaffected.

Fixes DSS-131

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• unit tests
• tested manually

Test Configuration:

• Pine versions: 3.15.3
• OS: macOS
• Browsers: Chrome

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes
• Design has QA'ed and approved this PR

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[pixelflips]

This is too heavy handed for now. Will close in favor or a different approach.