refactor: clean up, fix & remove outdated code

[LuanRT]

Description

This removes all references to legacy code from v1, including most of the utility methods from Actions and the old call method from NavigationEndpoint. This should make the library easier to maintain and less prone to bugs.

Also including a few fixes:

Support for YouTube Music's new library layout

YouTube Music recently received a layout update which caused @patrickkfkan's implementation to break, the page now consists of a simple header + contents configuration.

Usage:

// Retrieve the library 
const library = await yt.music.getLibrary();
console.log(library);

// Retrieve continuation
if (library.has_continuation) {
  const library_continuation = await library.getContinuation();
  console.log(library_continuation);
}

// Sort library content
const sorted_library = await library.applySortFilter('Recently played');
console.log(sorted_library);

// Filter library content
const filtered_library = await library.applyFilter('Albums');
console.log(filtered_library);

// Check available filters
console.log(library.sort_filters)
console.log(library.filters);

YouTube Playlists

The Innertube#getPlaylist method would usually return an invalid Playlist object and continuations could not be retrieved, this should fix that.

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This is a rather huge PR, so my apologies to anyone looking around here.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have checked my code and corrected any misspellings