Fix worker infinite retry

[vigoo]

Resolves #693

• Skip hint entries when calculating retry count (the number of errors at the end of the oplog) as they can interleave the errors (example: new incoming invocation)
• Not writing resource create/describe/drop entries in reply mode (this with the lack of the first point caused the infinite retry loop)
• Fixes an issue where a worker ends up idle when invoked with a non-existing function, as the error was returned earlier than writing the bad invocation to the oplog.

[vigoo]

Made it draft because I realized that the last point makes workers permanently failed if they get invoked with a wrong function name which we don't want. New fix coming to the PR soon.