docs: typedoc improvements

[erickzhao]

Cleanup PR based on learnings from the TypeDoc PRs.

• Direct use of npx typedoc rather than JavaScript API removes legacy build_docs.js from code. Their JavaScript API has minimal documentation, and most options are available via typedoc.json configuration anyways.
• Use of externalSymbolLinkMappings to show links to types available via external Electron packages (e.g. get and notarize).

Tag changes:

• Changed plaintext examples to use the @example tag.
• Fixed outstanding cases of legacy [[link tag syntax]] to use {@link tag syntax}.
• Used @interface to expand utility types whenever possible (e.g. instead of Omit<TypeA, 'KeyB' | 'KeyC'>, adding the @interface tag makes it so that all of TypeA's properties are displayed in the API documentation excluding KeyB and KeyC.
• Used @internal and excludeInternals to hide types that should not be used by end users of Electron Packager.

[malept]

Do we also need to add explicit external link config for osx-sign and windows-sign? Plus any other dependency where we proxy the options that I'm forgetting.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.06%. Comparing base (2f92bbd) to head (9080e0d).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1734 +/- ## ========================================== - Coverage 89.28% 89.06% -0.23% ========================================== Files 17 17 Lines 905 905 Branches 187 187 ========================================== - Hits 808 806 -2 - Misses 61 62 +1 - Partials 36 37 +1 ```

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