Ytdl-sub

[BUGFIX] Fix variable collision when disabling plugins (1072)

Fixes https://github.com/jmbannon/ytdl-sub/issues/1071

[BREAKING CHANGE] Remove regex plugin (1067)

Regex plugin has been removed in favor of scripting. The function [regex_capture_many](https://ytdl-sub.readthedocs.io/en/latest/config_reference/scripting/scripting_functions.html#regex-capture-many) has been created to replicate the plugin's behavior. See the following converted example:

`regex, now deprecated`

regex:
from:
title:
match:
- ".*? - (.*)" Captures 'Song' from 'Emily Hopkins - Some - Song'
capture_group_names:
- "captured_track_title"
capture_group_defaults:
- "{title}"
overrides:
track_title: "{captured_track_title}"


`scripting equivalent`

overrides:
Captures 'Song' from 'Emily Hopkins - Some - Song'
captured_track_title: >-
{
%regex_capture_many(
title,
[ ".*? - (.*)" ],
[ title ]
)
}
track_title: "{%array_at(captured_track_title, 1)}"


Motivation:
Regex was a unique plugin that added custom variables based on user input. This made the backend need to support both `overrides` and 'plugin user variables'. Removing `regex` plugin will consolidate this logic into only `overrides`, making it much easier to maintain.

[BACKEND] Proper functions with docstrings (1061)

Reimplement some of the 'hidden' functions, including `%regex_capture_many`, as standard functions with docstrings

[BACKEND] Add /usr/local/bin/ffmpeg as possible default location (1056)

For better cross-platform support

[BACKEND] `%contains_any` function, list + dict support for tilda overrides mode (1054)

Adds the function `%contains_any`, and list support in a tilda override subscription. The end-goal of these features are to more easily add a title exclude list, like so:


__preset__:
filter_exclude:
- "{%contains_any( %lower(title), exclude_title_strings )}"

...
Jellyfin TV Show by Date:
~History Documentaries:
url: "https://..."
exclude_title_strings:
- "trailer"
- "preview"


A proper prebuilt preset or built-in functionality will follow this change.

[BACKEND] get_file_md5_hash: read small blocks instead of the entire file (1052)

This prevents MemoryError when running on systems with less memory than the file being processed.

Fixes 1051. Thanks parkr