[tag tool] Large feature, support tagging all languages/scripts:

[davelab6]

• add a 'sample text' dropdown to select all sample_text keys except masthead_* and poster_*; if no sample_text then use exemplar_chars.base. Given use of notdef requested in Fix typos in Alata description #8131, users will see a lot of tofu, but that's OK to start; but to address it, then
• add 'writing system' and 'language' dropdowns to select scripts and languages, similar to the mock Tomas showed here, using data from https://github.com/googlefonts/lang, so users can filter the families (so families that don't support the script/language selected are no longer shown)

[m4rc1e]

We currently use the "The quick brown fox" pangram for every family. How about we simply provide a pangram selector that includes different scripts? Imo this is far easier to maintain in the long run. The individual doing the tagging will know what scripts are in the fonts anyway.

[m4rc1e]

Found a better way, I'll just choose the most appropriate pangram based on the PrimaryScript field for each family.

[m4rc1e]

Done.

[davelab6]

Sadly I am not seeing expected results :)

[davelab6]

based on the PrimaryScript field for each family.

Possibly the families with nothing showing have no Latin? And the ones with Latin samples have no PrimaryScript?