Implement app tagging system

[lberrymage]

Allow developers to add tags to their app like "requires GMS," or "open-source" for filtering and categorization. Arbitrary tag names should not be allowed; tag names should come from a predefined list of allowed values to ensure they're actually useful for filtering.

To-do:

• Define app tag representation in repodata
• Properly update tags when fetching repodata in client
• Allow developers to specify tags when submitting their app
• Implement tag filters in search function

This is an enhancement to accrescent/accrescent#21

[S7venLights]

See https://github.com/ImranR98/Obtainium for category tagging inspiration

Allowing the user to assign custom tags should help too as then every user can choose what they need

[loyl1]

Near the top of the page, possibly list
"popular tags"
"Open Source" "Communication" " etc
Can expand to "all tags"
In this way, those who follow open source religiously can hide all closed source apps. Possibly allow filter by multiple tags, like "open source" and "security"