Support querying all Data source-managed alerts

[dmyerscough]

Description

This change enables querying all Data source-managed, I tested this with Grafana Playground

Checklist

• The patch has appropriate test coverage
• The patch follows the style guidelines of this project
• The patch has appropriate comments, particularly in hard-to-understand areas
• The documentation was updated corresponding to the patch
• I have performed a self-review of this patch

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.34%. Comparing base (d554ba5) to head (298cd2e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #212   +/-   ##
=======================================
  Coverage   92.33%   92.34%           
=======================================
  Files          27       27           
  Lines        1814     1816    +2     
=======================================
+ Hits         1675     1677    +2     
  Misses        139      139           

Flag	Coverage Δ
unittests	92.34% <100.00%> (+<0.01%)	⬆️

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[amotl]

Thank you very much!

[amotl]

Your improvements have been included into grafana-client 4.3.0.