🐛 properly handle timing literals in QASM parser

[burgholzer]

Description

This PR fixes a bug in the QASM parser that would treat timing literal suffixes as individual tokens, which can lead to strange errors with gate declarations whose name matches a timing literal suffix, e.g., ms.
Timing literals are now properly treated and do not lead to clashes.

In the process, it was noticed that the Python import of long QASM strings would fail due to pathlib throwing an OSError for too long paths.
This is now fixed by short circuiting if the path is too long.

Fixes #723

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]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.2%. Comparing base (11a7d49) to head (896257d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #724     +/-   ##
=======================================
+ Coverage   92.1%   92.2%   +0.1%     
=======================================
  Files        125     125             
  Lines      13757   13739     -18     
  Branches    2150    2158      +8     
=======================================
+ Hits       12671   12678      +7     
+ Misses      1086    1061     -25     

Flag	Coverage Δ
cpp	92.0% <100.0%> (+0.1%)	⬆️
python	99.7% <100.0%> (+<0.1%)	⬆️

Files with missing lines	Coverage Δ
...clude/mqt-core/ir/parsers/qasm3_parser/Scanner.hpp	71.4% <ø> (ø)
include/mqt-core/ir/parsers/qasm3_parser/Token.hpp	98.2% <100.0%> (-0.1%)	⬇️
src/ir/parsers/qasm3_parser/Parser.cpp	92.6% <100.0%> (-0.1%)	⬇️
src/ir/parsers/qasm3_parser/Scanner.cpp	97.0% <100.0%> (+0.1%)	⬆️
src/mqt/core/__init__.py	100.0% <100.0%> (ø)

... and 16 files with indirect coverage changes