fix(codegen): generate string literal unions for Enums (#95)

[rockaxorb13]

Description

This PR updates the TypeScript generator to output String Union Types (e.g., type State = 'NY' | 'NJ';) instead of TypeScript enum declarations. This aligns the output with modern TypeScript best practices and resolves issue #95.

Changes

• Modified TypescriptVisitor: The visitor now generates export type <Name> = 'Value1' | 'Value2'; syntax for enum declarations.
• Updated Unit Tests: Updated typescriptvisitor.js test mocks to support the new logic (specifically adding .getName() to property mocks) and verify the correct output format.

Fixes

Fixes #95

Note on Snapshots

I verified the logic is correct via local testing (see the diff below), but I was unable to commit the updated .snap files because my local environment is locked in CI mode and refuses to write new snapshots.

Verification (npm test output):
As you can see, the generated output (Received) correctly matches the desired String Union syntax:

  564 passing (12s)
  2 failing

  1) codegen
       #formats
         check we can convert all formats from namespace versioned CTO, format 'typescript':
     Error: expect(received).toMatchSnapshot()

Snapshot name: `codegen #formats check we can convert all formats from namespace versioned CTO, format 'typescript' 4`

- Snapshot  - 15
+ Received  +  5

@@ -15,24 +15,15 @@
  export type CategoryUnion = IGeneralCategory;

  export interface IGeneralCategory extends ICategory {
  }

- export enum State {
-    MA = 'MA',
-    NY = 'NY',
-    CO = 'CO',
-    WA = 'WA',
-    IL = 'IL',
-    CA = 'CA',
- }
+ export type State =
+    'MA' | 'NY' | 'CO' | 'WA' | 'IL' | 'CA';

- export enum TShirtSizeType {
-    SMALL = 'SMALL',
-    MEDIUM = 'MEDIUM',
-    LARGE = 'LARGE',
- }
+ export type TShirtSizeType =
+    'SMALL' | 'MEDIUM' | 'LARGE';

  export type EmployeeTShirtSizes = Map<string, ITShirtSizeType>;

  export interface IAddress extends IConcept {
     street: string;
@@ -40,10 +31,9 @@
     state?: State;
     zipCode: string;
     country: string;
  }

- export enum Level {
- }
+ export type Level = never;

  ",
  }
      at /home/axorb_13/accord_project/concerto-codegen/test/codegen/codegen.js:70:41
      at Map.forEach (<anonymous>)
      at Context.<anonymous> (test/codegen/codegen.js:69:23)
      at process.processImmediate (node:internal/timers:504:21)

  2) codegen
       #formats
         check we can convert all formats from namespace unversioned CTO, format 'typescript':
     Error: expect(received).toMatchSnapshot()

Snapshot name: `codegen #formats check we can convert all formats from namespace unversioned CTO, format 'typescript' 4`

- Snapshot  - 15
+ Received  +  5

@@ -15,24 +15,15 @@
  export type CategoryUnion = IGeneralCategory;

  export interface IGeneralCategory extends ICategory {
  }

- export enum State {
-    MA = 'MA',
-    NY = 'NY',
-    CO = 'CO',
-    WA = 'WA',
-    IL = 'IL',
-    CA = 'CA',
- }
+ export type State =
+    'MA' | 'NY' | 'CO' | 'WA' | 'IL' | 'CA';

- export enum TShirtSizeType {
-    SMALL = 'SMALL',
-    MEDIUM = 'MEDIUM',
-    LARGE = 'LARGE',
- }
+ export type TShirtSizeType =
+    'SMALL' | 'MEDIUM' | 'LARGE';

  export type EmployeeTShirtSizes = Map<string, ITShirtSizeType>;

  export interface IAddress extends IConcept {
     street: string;
@@ -40,10 +31,9 @@
     state?: State;
     zipCode: string;
     country: string;
  }

- export enum Level {
- }
+ export type Level = never;

  ",
  }
      at /home/axorb_13/accord_project/concerto-codegen/test/codegen/codegen.js:97:41
      at Map.forEach (<anonymous>)
      at Context.<anonymous> (test/codegen/codegen.js:96:23)
      at process.processImmediate (node:internal/timers:504:21)




=============================== Coverage summary ===============================
Statements   : 99.16% ( 2985/3010 )
Branches     : 96.22% ( 1451/1508 )
Functions    : 99.6% ( 507/509 )
Lines        : 99.19% ( 2950/2974 )
================================================================================
[axorb_13@axorb-linux concerto-codegen]$ 

I tried updating the snap files, using different flags and even some modifications in the file:
/concerto-codegen/test/codegen/codegen.js

But to no avail as of now.