Adding relax max_step widget

[AndresOrtegaGuerrero]

This pull request addresses issue #748 by introducing a widget that allows users to set the maximum number of steps for structural relaxation calculations in Quantum ESPRESSO. The default is 50 steps, but some systems may require more to achieve convergence. This feature prevents premature termination of calculations due to insufficient iteration limits. Additionally, systems requiring tighter convergence criteria, such as those involved in phonon calculations, may benefit from increased step limits.

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.

Project coverage is 67.88%. Comparing base (084431f) to head (441feb3).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...aiidalab_qe/app/configuration/advanced/advanced.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1063      +/-   ##
==========================================
+ Coverage   67.86%   67.88%   +0.01%     
==========================================
  Files         112      112              
  Lines        6668     6675       +7     
==========================================
+ Hits         4525     4531       +6     
- Misses       2143     2144       +1     

Flag	Coverage Δ
python-3.11	67.88% <71.42%> (+0.01%)	⬆️
python-3.9	67.90% <71.42%> (+0.01%)	⬆️

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[edan-bainglass]

@AndresOrtegaGuerrero this ready?

[AndresOrtegaGuerrero]

yes

[edan-bainglass]

LGTM!