Description of problem:

Admin should be able to edit recommended language sets, so project maintainer can quickly setup frequently used languages.

Currently in Zanata, "Enabled by default" is the attempt to hide rarely used languages from users and zanata.xml.

However,  "Enabled by default" only allow 2 useful choices: either those "Enabled by default", or all. If you have more that two teams that require different language sets, you can only please one of them and other teams need to configure it by hand, which is inconvenient.

With capability of providing the language sets, project maintainers can quickly select the languages that their platform supported.

The recommended language sets should be available to all the project maintainers.

The feature for group or organization maintainers to edit recommend language sets should be addressed in other bugs.

Version-Release number of selected component (if applicable):
3.5