Fallback to the root bundle when no locales are configured

[agubler]

Type: bug

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier as per the readme code style guidelines
• Unit or Functional tests are included in the PR

Description:

• Use a basic message loader when i18n has not been configured for the application.
• Load the fallback cldr for unknown locales that are passed to localizeBundle but not set through changing the local via the i18n middleware or mixin.

[codesandbox-ci]

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[codecov]

Codecov Report

Merging #677 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #677      +/-   ##
==========================================
- Coverage   97.80%   97.78%   -0.03%     
==========================================
  Files         117      117              
  Lines        6570     6585      +15     
  Branches     1494     1500       +6     
==========================================
+ Hits         6426     6439      +13     
- Misses        144      146       +2     

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