dialects: (stream) simplify constr helper on stream attributes

[superlopuh]

I'm working towards removing the stream dialect, and would like to simplify it as much as possible before copying to both memref_stream and snitch_stream. I don't think the constr overload is pulling its weight, it's much simpler just to provide a shorthand for the BaseAttr constraint, and only return a ParamAttrConstraint from constr.

[superlopuh]

I have a feeling that this will be the pattern to use until we have defaults for TypeVars

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.33%. Comparing base (ee4094f) to head (1307bd4).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3473      +/-   ##
==========================================
+ Coverage   90.32%   90.33%   +0.01%     
==========================================
  Files         464      464              
  Lines       58079    58057      -22     
  Branches     5565     5556       -9     
==========================================
- Hits        52458    52446      -12     
+ Misses       4188     4185       -3     
+ Partials     1433     1426       -7     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[alexarice]

If someone is brave at some point, we could also think about auto-generating these constr helpers