fix 🐛 Fix bug on "gate" in gate names

[DRovara]

Description

Previously, the debugger checked whether an instruction is a custom gate definition by testing if its text contains "gate ". Of course, this could fail if a custom gate or a register name ends with "gate".

With this pull request, we now store a set of custom gate definitions instead. Now, only the CodePreprocessor has to check for the "gate" keyword, and in this step, we have access to the tokenized code, so when we encounter the "gate" token, we can be sure it is actually a custom gate.

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.4%. Comparing base (89928c6) to head (5301615).

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Additional details and impacted files

@@           Coverage Diff           @@
##            main      #8     +/-   ##
=======================================
+ Coverage   65.1%   70.4%   +5.3%     
=======================================
  Files         13      13             
  Lines       1599    1599             
  Branches     230     229      -1     
=======================================
+ Hits        1042    1127     +85     
+ Misses       557     472     -85     

Flag	Coverage Δ		*Carryforward flag
cpp	78.0% <100.0%> (+6.0%)	⬆️
python	18.7% <ø> (ø)		Carriedforward from 89928c6

*This pull request uses carry forward flags. Click here to find out more.

Files	Coverage Δ
src/backend/dd/DDSimDebug.cpp	83.0% <100.0%> (+4.0%)	⬆️
src/common/parsing/CodePreprocessing.cpp	96.4% <100.0%> (ø)

... and 1 file with indirect coverage changes