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

aio/tools/transforms/cli-docs-package/readers/cli-command.js

@@ -15,6 +15,7 @@ module.exports = function cliCommandFileReader(log) {
     name: 'cliCommandFileReader',
     defaultPattern: /\.json$/,
     getDocs(fileInfo) {
+      fileInfo.realProjectRelativePath = 'packages/angular/cli/commands/' + fileInfo.relativePath;
       try {
         const doc = json5.parse(fileInfo.content);
         const name = fileInfo.baseName;
@@ -23,7 +24,6 @@ module.exports = function cliCommandFileReader(log) {
         const result = Object.assign(doc, {
           content: doc.description,
           docType: 'cli-command',
-          startingLine: 1,
           id: `cli-${doc.name}`,
           commandAliases: doc.aliases || [],
           aliases: computeAliases(doc),