chore(deps): upgrade frontend to Angular 20

[aglinxinyuan]

What changes were proposed in this PR?

Upgrade the frontend from Angular 19 to Angular 20 and make the supporting compatibility fixes needed for the current Texera app, build, and test setup.

• Upgraded Angular packages to Angular 20
  • @angular/*
  • @angular/cli
  • @angular-devkit/*
  • @angular/cdk
• Updated related frontend tooling and ecosystem packages
  • ng-zorro-antd
  • ngx-markdown
  • @angular-builders/custom-webpack
  • @angular-eslint/*
  • typescript
  • @types/node
  • y-websocket
• Applied Angular migration updates
  • updated angular.json
  • updated TS config for Angular 20 compatibility
• Fixed Angular 20 app/module issues
  • removed invalid NzMessageModule import usage
  • restored correct AppModule declarations/imports
• Fixed typing and compatibility issues in editor/debugger code
  • Monaco type imports
  • Yjs / y-websocket typings
  • interval/timer typing updates
• Updated affected specs to pass under Angular 20
  • replaced outdated Angular testing APIs where needed
  • simplified Monaco-heavy tests to avoid brittle runtime setup
• Kept the existing app structure intact instead of doing a broader standalone migration

Any related issues, documentation, discussions?

Closes #4432

How was this PR tested?

• yarn --cwd frontend format:ci
• yarn --cwd frontend run build:ci
• yarn --cwd frontend run test:ci

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Codex

[Xiao-zhen-Liu]

LGTM.