fix(fast-element): preserve context on same-source rebinds

[janechu]

Pull Request

📖 Description

Updates HTMLView and HydrationView so binding the same source with a different execution context refreshes the view context instead of taking the no-op fast path. The existing no-op behavior is preserved when both source and context are unchanged, with focused standard and hydrated view coverage plus design documentation.

📑 Test Plan

• npm run build:tsc -w @microsoft/fast-element
• npx playwright test --project=chromium -g "updates context when binding the same source with a new context|updates hydrated view context"
• npx biome check packages\fast-element\src\templating\view.ts packages\fast-element\src\templating\hydration-view.ts packages\fast-element\src\templating\view.pw.spec.ts
• npm run checkchange

✅ Checklist

General

• I have included a change request file using $ npm run change
• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.