fix(api/schedule): make validateEntry more strict and set updated_by using claims

[ecrupper]

Prior to this change, the entry 0 1,2,10,12 * * * with a VELA_SCHEDULE_MINIMUM_FREQUENCY of 180m would be considered valid if you added the schedule between the hours of 12:00 Zulu time and 1:00 Zulu time the next day. Won't catch all cases, but I figured it would catch more than enough.

Also set updated_by in the update schedule endpoint.

[codecov]

Codecov Report

Merging #901 (165407e) into main (900608b) will decrease coverage by 0.01%.
The diff coverage is 57.14%.

❗ Current head 165407e differs from pull request most recent head 6c5b7b4. Consider uploading reports for the commit 6c5b7b4 to get more accurate results

@@            Coverage Diff             @@
##             main     #901      +/-   ##
==========================================
- Coverage   71.48%   71.47%   -0.01%     
==========================================
  Files         304      304              
  Lines       12438    12450      +12     
==========================================
+ Hits         8891     8899       +8     
- Misses       3116     3120       +4     
  Partials      431      431              

Impacted Files	Coverage Δ
api/schedule/update.go	0.00% <0.00%> (ø)
api/schedule/create.go	14.39% <66.66%> (+5.52%)	⬆️