feat(core): [CNX-9108] Added server migration support

[JR-Morgan]

Added server migration properties to server info
Added new function in Credentials.py get_account_for_server(host: str)
Added unit test (mimicking the C# one) to test above function

Equivalent to the specklesystems/speckle-sharp#3201 and specklesystems/speckle-sharp#3216

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.32%. Comparing base (1b59f0b) to head (66dc076).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #331      +/-   ##
==========================================
+ Coverage   90.22%   90.32%   +0.09%     
==========================================
  Files          94       95       +1     
  Lines        5578     5633      +55     
==========================================
+ Hits         5033     5088      +55     
  Misses        545      545              

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