This is a quick fix to a long standing problem of
`org.enso.interpreter.service.error.FailedToApplyEditsException` which would prevent backend from processing any more changes, rendering GUI (and backend) virtually useless.
Edits are submitted for (background) processing in the order they are handled. However the order of execution of such tasks is not guaranteed. Most of the time edits are processed in the same order as their requests but when they don't, files get quickly out of sync.
Related to #8770.
# Important Notes
I'm not a fan of this change because it essentially blocks all open/file requests until all edits are processed and we already have logic to deal with that appropriately. Moreover those tasks can and should be processed independently. Since we already had the single thread executor present to ensure correct synchronization of open/file/push commands, we are simply adding edit commands to the list.
Ideally we want to have a specialized executor that executes tasks within the same group sequentially but groups of tasks can be executed in parallel, thus ensuring sufficient throughput. The latter will take much longer and will require significant rewrite of the command execution.
Added tests that would previously fail due to non-deterministic execution.
