Support creating report for saved objects with custom id

[zhongnansu]

Issue #, if available:
#252 #250

Description of changes:

• refactor the regex for url validation, which removes the part that validates the saved object id to be strict uuid
• instead, add one more step to use the exists API to verify if the saved_objec_id actually exists in ES.
• Add unit tests

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

Merging #283 (f803b9e) into dev (45abee7) will increase coverage by 0.18%.
The diff coverage is 86.66%.

@@            Coverage Diff             @@
##              dev     #283      +/-   ##
==========================================
+ Coverage   74.94%   75.12%   +0.18%     
==========================================
  Files          32       32              
  Lines        1764     1793      +29     
  Branches      342      347       +5     
==========================================
+ Hits         1322     1347      +25     
- Misses        437      441       +4     
  Partials        5        5              

Impacted Files	Coverage Δ
kibana-reports/server/utils/validationHelper.ts	89.18% <86.66%> (-10.82%)	⬇️

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