[FEATURE] Allow YAML maps and lists in overrides, convert to script format

[jmbannon]

Adds the ability to create map and list-based override variables.

For example, you can now create lists like this:

overrides:
  urls:
    - "https://...1"
    - "https://...2"

which is equivalent to:

overrides:
  urls: >-
    {
      [
        "https://...1",
        "https://...2",
      ]
    }

Likewise, maps can now look like:

overrides:
  music_video_category:
    concerts:
      - "https://...1"
      - "https://...2"
    interviews:
      - "https://...3"

which is equivalent to:

overrides:
  music_video_category: >-
    {
      "concerts": [
        "https://...1",
        "https://...2"
      ],
      "interviews": [
        "https://...3"
      ]
    }

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 95.94595% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 96.76%. Comparing base (64d3082) to head (2fc7236). Report is 8 commits behind head on master.

:exclamation: Current head 2fc7236 differs from pull request most recent head 29fd730

Please upload reports for the commit 29fd730 to get more accurate results.

Files	Patch %	Lines
src/ytdl_sub/utils/script.py	96.55%	2 Missing :warning:
src/ytdl_sub/script/parser.py	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #956 +/- ## ========================================== - Coverage 96.77% 96.76% -0.01% ========================================== Files 115 115 Lines 7381 7451 +70 ========================================== + Hits 7143 7210 +67 - Misses 238 241 +3 ```

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