Request accept buttons into dropdown

[ncounter]

Depends on #16960

Only the last commit contains this relevant PR change

The proposal is about keeping separated all the different decision actions, but grouping the accept request ones. Accepting request can be made like:

1. Accept
2. 1+ make the submitter a maintainer of the target project/package
3. 1+ forward to projects
4. 1+2+3 (Accept + make maintainer + forward)

Due to the fact that the forward can be submitted to multiple choices, they requires checkboxes to be visible and selectable, thus the separated dropdown for the accept+forwards options