Added type assertion for json files

PR Checklist

• Addresses an existing open issue: fixes Bug: [consistent-type-imports] Incorrectly suggests import type on import assertion #7527
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

This PR addresses the issue where typescript-eslint/eslint-plugin throws an error when an import statement with type imports includes an import assertions.

Reproduction Code:

import * as aJson from './a.json' assert { type: 'json' }

const what: aJson.A;

Actual Behaviour

typescript-eslint provides an invalid TypeScript code as a fix and hence had to be addressed by adding a rule that checks for such import type assertions.

Expected Behaviour

Since typescript 4.5, import assertions are supported, so No Error or All is Ok is the expected output.

Changes made:

1. Modified rule in consistent-type-imports.ts for type only import. Now it checks for absence of assertions and only then suggests the fix.

// checks for presence of import assertions
if (node.assertions.length === 0) {
  yield * fixInsertTypeSpecifierForImportDeclaration(fixer, node, false);
}

2. Tweaked reporting conditions in consistent-type-imports.ts for type only imports. Now it checks for absence of import assertions and only then reports the error.

/** checks if import has type assertions
 * ```
 * import * as type from 'mod' assert { type: 'json' };
 * ```
 * https://github.com/typescript-eslint/typescript-eslint/issues/7527
 */
if (report.node.assertions.length === 0) {
  context.report({
    node: report.node,
    messageId: "typeOverValue",
    *fix(fixer) {
      yield* fixToTypeImportDeclaration(fixer, report, sourceImports);
    }
  });
}

3. Added a rule to consistent-type-imports.test.ts which considers import assertion for json files as a valid rule.

  {
    code: `
      import * as Type from 'foo' assert { type: 'json' };
      const a: typeof Type = Type;
    `,
    options: [{ prefer: 'no-type-imports' }],
    dependencyConstraints: {
      typescript: '4.5',
    },
  },