[MOB-10381] Migrate Sinon's fake XHR to Nock and XHR polyfill

[a7medev]

Description of the change

Migrates Sinon's fake/mock XMLHttpRequest to Nock request mocking and a Node XHR polyfill (xhr2).

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

Issue links go here

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests

Code review

• This pull request has a descriptive title and information useful to a reviewer
• Issue from task tracker has a link to this pull request

[codecov]

Codecov Report

Merging #795 (7672fd6) into master (875e79e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #795   +/-   ##
=======================================
  Coverage   86.54%   86.54%           
=======================================
  Files          14       14           
  Lines         602      602           
  Branches      103      103           
=======================================
  Hits          521      521           
  Misses         68       68           
  Partials       13       13           

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