Included tag directive in Apollo Federation import list

[glen-84]

Summary of the changes (Less than 80 chars)

• Included tag directive in Apollo Federation import list.

Closes #7413

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@michaelstaib This is roughly what we discussed, but it's probably not correct, since I assume that it should only be included when the tag directive is used in the schema? If so, is there an easy way to check that?

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 77.95%. Comparing base (256dd07) to head (a2f1e87).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
.../src/ApolloFederation/FederationTypeInterceptor.cs	93.75%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7421   +/-   ##
=======================================
  Coverage   77.95%   77.95%           
=======================================
  Files        2836     2836           
  Lines      142551   142562   +11     
=======================================
+ Hits       111129   111139   +10     
- Misses      31422    31423    +1     

Flag	Coverage Δ
unittests	77.95% <93.75%> (+<0.01%)	⬆️

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