feat!: Return the type of FuncDecl in HugrView::get_function_type

[aborgna-q]

get_function_type was confusing, as it didn't specify that it only worked for dataflow containers, and required manually checking for function declarations on the side.

BREAKING CHANGE: HugrView::get_function_type now returns a PolyFuncType.

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 85.57%. Comparing base (d5294ad) to head (0a3aa78).
Report is 1 commits behind head on main.

Files	Patch %	Lines
quantinuum-hugr/src/hugr/views.rs	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #880      +/-   ##
==========================================
+ Coverage   85.49%   85.57%   +0.07%     
==========================================
  Files          78       78              
  Lines       14456    14458       +2     
  Branches    14456    14458       +2     
==========================================
+ Hits        12359    12372      +13     
+ Misses       1460     1450      -10     
+ Partials      637      636       -1     

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[ss2165]

We discussed this a lot in #754 and the follow up #782

I still think that getting a FunctionType when applicable rather than a PolyFuncType is useful, and the latter only applies to two node types. I would perhaps suggest a non-breaking additional function that does what you want.

[aborgna-q]

Could the previous get_function_type be renamed to get_df_function_type or something similar?
I had to spend some time tracking down the function calls to see why the FuncDecl match was necessary.

#881 will use this generic version in multiple places.

[ss2165]

yeah I don't mind that