Migrate to Azure Functions Elastic Premium plan

[lamaks]

This pull request primarily removes the parallel-workers package from the repository and cleans up related code and configuration. Additionally, it refines error reporting in Azure credential management and streamlines hash generation logic by removing unused methods. Below are the most important changes grouped by theme:

Parallel-workers package removal:

• Deleted the entire packages/parallel-workers directory, including all source files, configuration files, and tests. [1] [2] [3] [4] [5] [6] [7]
• Removed references to parallel-workers from workspace configuration files, build scripts, and package lists (.vscode/workspace.code-workspace, package.json, and related test/build configs). [1] [2] [3]

Hash generator simplification:

• Removed unused hash generation methods (getWebsiteScanResultDocumentId, getWebsiteScanResultPartDocumentId, and related test cases) from packages/common/src/ciphers/hash-generator.ts and packages/crawler/src/common/hash-generator.ts. [1] [2] [3] [4]
• Cleaned up imports in packages/crawler/src/common/hash-generator.ts by removing unused dependencies.

Azure credential error reporting:

• Improved error messages in IdentityCredentialCache to provide more context, including client ID, scope, and stack trace. Updated corresponding test to match the new error message. [1] [2]

OpenAPI contract adjustment:

• Updated packages/api-contracts/openapi.json to remove the scanType property from one schema and restrict its enum to "accessibility" in another, reflecting a change in supported scan types. [1] [2]

Build and ignore file updates:

• Broadened the ignore pattern for .txt files in .prettierignore and adjusted the clean script in package.json to remove fewer directories. [1] [2]