[Feature] Match multiple sources for manual rom matching

When you manually match roms, it is possible to get matches from different metadata providers that differ from one another. You are given the option to select which source to use. Metadata providers are then also grouped together sometimes when the rom name matches. Obviously this functionality is to allow for selecting the correct metadata match as some sources will have false positives, but there are times when you will get multiple selection options where some or all are correct but the metadata source just uses a different name not recognized by the others.

Currently the only way to add metadata sources that are excluded for whatever reason but are otherwise correct is to manually enter the ID, as running the rom match again and selecting the other sources will overwrite the metadata linked (though somewhat annoyingly will leave linked media). This can be tedious, and as far as I am aware adding the ID won't then pull metadata and media you may desire. Adding in the functionality to select multiple sources, as well as exclude sources that are grouped together can help with adding a more complete list of sources and fix some false positives.

It is a pretty minor issue overall, but there are cases where different metadata providers will have different levels of accuracy and quality with some metadata and media but you otherwise can't apply because romm does not group them together for whatever reason, especially with Japanese games where rom name matches can be in hiragana/katakana or romaji (and with different romanizations as well such as the common L vs R syllable translation issues), as well as with unlicensed games where quality and accuracy can be all over the place.