Change branching strategy to trunk-based

[simskij]

To simplify the workflow, we should change the branching strategy to trunk-based + short-lived feature branches instead of the current feature -> dev (and staging) -> master (and prod) approach.

The new branching strategy means that features will be merged directly to master, which in turn will be released in staging. Tagging a commit in master with a version number will release it to production. For instance:

master will be released to staging, but not feature/whatever.
v1.2.3 will be released to production, but not an-arbitrary-tag.

[imiric]

Could we increase the priority of this? This cherry-picking and dual PR approach is difficult, and can lead to discrepancy issues between staging and prod.

[simskij]

@ppcano - thoughts? ☝🏼

[mostafa]

I am all pro this change.