docs: Migrate link formats

What

Migrates the formats of links in Markdown content as part of the Docs Content Link Rewrites project
Adds two new GitHub workflow files:
- .github/workflows/check-legacy-links-format.yml - This is a workflow that checks if links in markdown content are in the new format. It does this by running the link rewrite script from dev-portal, and then asserting that no "rewriteable" links were found. This workflow will be used on subsequent PRs to maintain the new link format.
- .github/workflows/test-link-rewrites.yml - This is a workflow that executes e2e tests of this PR's changes against the main branch's deploy preview. The tests only run for branches named docs/amb.migrate-link-formats, so future PRs will not have the tests run against them. This is a temporary workflow.

With the two new workflows in place, this PR should only need a spot-check.

[ ] The latest run of the "Legacy Link Format Checker" workflow for this branch should pass (check here)
[ ] The latest run of the "Test Link Rewrites" workflow for this branch should pass (check here)

To see the specific tasks where the Asana app for GitHub is being used, see below:
- https://app.asana.com/0/0/1203534392784695
- https://app.asana.com/0/0/1203715368770951