RUMM-2770: Improve mapping upload flow handling

[0xnm]

What does this PR do?

This change improves mapping upload flow handling by doing the following:

• Additional check for the API key validity is done (using API key validation API) if server returns code 400, this is basically aligns logic with datadog-ci.
• Removed a statement saying that server may already have mapping uploaded - server will never return error if there is already mapping uploaded.
• Added an additional check for quotes\apostrophes in API key, this may be useful for the error investigation on the client side (this check is quite limited to only quotes and apostrophes, because there is no public contract for the API key format).
• Added a site name to the upload info message (and to some other messages as well).

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• [ ] Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #131 (8268d10) into develop (5d67abb) will decrease coverage by 1.20%. The diff coverage is 75.61%.

@@              Coverage Diff              @@
##             develop     #131      +/-   ##
=============================================
- Coverage      87.45%   86.25%   -1.20%     
- Complexity       169      174       +5     
=============================================
  Files             21       21              
  Lines            526      560      +34     
  Branches          65       72       +7     
=============================================
+ Hits             460      483      +23     
- Misses            42       49       +7     
- Partials          24       28       +4     

Impacted Files	Coverage Δ
...in/kotlin/com/datadog/gradle/plugin/DatadogSite.kt	84.62% <0.00%> (-15.38%)	:arrow_down:
...m/datadog/gradle/plugin/DdMappingFileUploadTask.kt	88.49% <75.00%> (-0.48%)	:arrow_down:
...m/datadog/gradle/plugin/internal/OkHttpUploader.kt	82.52% <77.78%> (-3.78%)	:arrow_down: