Foreign keys should be of same type as the primary key they reference

[noahhl]

Ran into the same issue as linkml/linkml/#1407 -- if you have a schema like:

ClassA:
   attributes:
      id:
          identifier: true
          range: integer
ClassB:
   attributes:
      other_model:
         range: ClassA

This was generating a foreign key on ClassB of type text in all SQL derivatives, even though the key that references is an integer. This pull request switches it so foreign keys are specified by the datatype of the identifier they link to.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7140555) 80.05% compared to head (b77e622) 80.05%.
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1907   +/-   ##
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  Coverage   80.05%   80.05%           
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  Files         100      100           
  Lines       11500    11503    +3     
  Branches     2968     2903   -65     
=======================================
+ Hits         9206     9209    +3     
  Misses       1738     1738           
  Partials      556      556           

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[cmungall]

much appreciated!