core: Make printer scoped.

[PapyChacal]

Fixes #2609
See https://xdsl.zulipchat.com/#narrow/stream/364199-Beginners/topic/SSA.20Value.20name.20re-use.20is.20broken : please, come in and enjoy updating the filechecks 😉

This will indeed make future works less tedious!

On the changes:

• Switch anonymous ssa_value/basic_block counters to stacks of counters
• Switch name_hint disambiguation counters to stacks
• Implement and expose enter_scope and exit_scope, simply pushing and popping on those stacks. So it's usable in different places if somebody wants to have fun in custom syntax? We can make those private first I guess
• Use those in operation printing (Printer.print_op, after the results are printed!) to scope if the printed op happens to be IsolatedFromAbove

[AntonLydike]

Thank you so much for this 👏 👏 👏

[AntonLydike]

I'm gonna take a shot at the failing tests that I know about

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.58%. Comparing base (3b5343a) to head (fbc481e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2614   +/-   ##
=======================================
  Coverage   89.58%   89.58%           
=======================================
  Files         360      360           
  Lines       45959    45974   +15     
  Branches     6954     6960    +6     
=======================================
+ Hits        41171    41186   +15     
  Misses       3717     3717           
  Partials     1071     1071           

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[math-fehr]

Really cool!