[7.x] Implement AnonymousAuthenticationProvider. (#79985)

[azasypkin]

Backports the following commits to 7.x:

• Implement AnonymousAuthenticationProvider. (Implement AnonymousAuthenticationProvider. #79985)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: c190343

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
security	470	471	+1

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
security	785.9KB	788.6KB	+2.6KB

Distributable file count

id	before	after	diff
default	43356	43357	+1

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
security	163.3KB	163.7KB	+422.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream