Ytdl-sub

[BUGFIX] Actually fix `subscription_name` with periods in it (861)

Prior PR did not actually work - this actually fixes the bug (https://github.com/jmbannon/ytdl-sub/issues/844) where subscription names would drop periods from them, i.e. Mr. Beast would have the name Beast.

POTENTIAL BREAKING CHANGE
If you have a subscription with a period in its name prior to this fix, this change will make it so your download archive is not found since it uses the subscription name in the download archive file path. To fix, simply change the download archive JSON's name to have the actual subscription name, and not the dropped-period one.

[REFACTOR] Organize variable definitions (860)

[FEATURE] `subscription_map` value (859)

To be used later for advanced presets. For subscriptions in the form of (+ as prefix)


+ Subscription Name:
Music Videos:
- "https://url1.com/..."
Concerts:
- "https://url2.com/..."


Stores all the contents under the subscription name into the override variable
``subscription_map`` as a Map value. The above example is stored as:


{
"Music Videos": [
"https://url1.com/..."
],
"Concerts: [
"https://url2.com/..."
]
}


Advanced scripting is needed to dissect this Map variable into a usable preset

[BUGFIX] Fix periods not working in subscription names (857)

Fixes the bug (844) where subscription names would drop periods from them, i.e. Mr. Beast would have the name Beast.

POTENTIAL BREAKING CHANGE
If you have a subscription with a period in its name prior to this fix, this change will make it so your download archive is not found since it uses the subscription name in the download archive file path. To fix, simply change the download archive JSON's name to have the actual subscription name, and not the dropped-period one.

[BACKEND] Remove subscription `__value__` (856)

Removes the deprecated `__value__` field in the subscriptions file (different from `__preset__` which is NOT deprecated). This was very short-lived, and most likely not used.

[BACKEND] Make sibling metadata optional to compute (855)

Partial fix to https://github.com/jmbannon/ytdl-sub/issues/853
Makes computing sibling metadata optional, defaulted to False. This prevents excessive memory usage when scraping large channels