build(docs-infra): display github links in CLI API docs (#26515)

This commit includes the following changes:

* CLI version information is read from the CLI package from which
  we read the help files.
* CLI API pages now contain GH links
* line numbers are not shown in GH links, if the doc does not
  have a truthy `startingLine` value. This allows us to remove
  hard coded checks for `guide` pages
* content pages and CLI api docs no longer have a `startingLine`
* the hard-coded `packages` path segment has been removed from
  the templates; instead we now only use the `realProjectRelativePath`.
* the `realProjectRelativePath` has been updated accordingly for API
  and CLI API docs.

PR Close #26515

scripts/ci/test-aio-tools.sh

@@ -10,6 +10,7 @@ source ${thisDir}/_travis-fold.sh
 travisFoldStart "test.docs"
   (
     cd ${PROJECT_ROOT}/aio
+    yarn setup
     yarn tools-test
   )
 travisFoldEnd "test.docs"