change color when visited and add icon to all external links

[RishhiB]

AB#1442

[ssimic2]

It would be nice to add some description to the PR and share images of the diff if the changes are visual in nature,

[Josmithr]

It would probably be good to add a brief overview to the PR description, since ADO links will not be usable by the open-source community.

[github-actions[bot]]

🔗 Found some broken links! 💔

Run a link check locally to find them. See https://github.com/microsoft/FluidFramework/wiki/Checking-for-broken-links-in-the-documentation for more information.

linkcheck output

> [email protected] linkcheck /home/runner/work/FluidFramework/FluidFramework/docs
> npm run linkcheck:fast -- --external


> [email protected] linkcheck:fast /home/runner/work/FluidFramework/FluidFramework/docs
> linkcheck http://localhost:1313 --skip-file skipped-urls.txt "--external"

Crawling...

http://localhost:1313/docs/apis/core-interfaces/ifluidcodedetailscomparer-interface
- (874:360) 'Array.sort' => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Description (HTTP 200 but missing anchor)
- (885:168) 'https://..' => https://github.com/npm/node-semver#usage (HTTP 200 but missing anchor)
- (893:25) 'Array.sort' => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Description (HTTP 200 but missing anchor)
- (939:25) 'https://..' => https://github.com/npm/node-semver#usage (HTTP 200 but missing anchor)

http://localhost:1313/docs/apis/core-interfaces/ifluidcodedetailscomparer-interface/
- (874:360) 'Array.sort' => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Description (HTTP 200 but missing anchor)
- (885:168) 'https://..' => https://github.com/npm/node-semver#usage (HTTP 200 but missing anchor)
- (893:25) 'Array.sort' => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Description (HTTP 200 but missing anchor)
- (939:25) 'https://..' => https://github.com/npm/node-semver#usage (HTTP 200 but missing anchor)


Stats:
  125441 links
    1324 destination URLs
       2 URLs ignored
       8 warnings
       0 errors

[github-actions[bot]]

This commit is queued for merging with the next branch! Please ignore this PR for now. Contact @microsoft/fluid-cr-infra for help.