Make laser parameters configurable; utility function for tunable laser

[oczoske]

The laser parameters (wavelength, power) are now taken from wcu.meta, i.e. from a config file or from kwargs.
All parameters can be changed by doing, e.g.

wcu = metis['wcu_source']
wcu.meta['laser_l_wave'] = 3.15
wcu.set_lamp("laser")

set_lamp is necessary to recompute the lamp emission.

The wavelengths of the tunable laser should be more easily accessible to the user, therefore a utility method is offered (this recomputes the emission automatically):

wcu.tune_laser(wavelength=np.linspace(4.68, 4.78, 10))

A validation method for the wavelengths has been implemented but is not yet used as we do not have reliable information on the actually available wavelength range.

[codecov]

Codecov Report

❌ Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.92%. Comparing base (5b85425) to head (9684627).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
scopesim/effects/metis_wcu/metis_wcu.py	92.59%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #970      +/-   ##
==========================================
+ Coverage   75.89%   75.92%   +0.03%     
==========================================
  Files          70       70              
  Lines        9030     9050      +20     
==========================================
+ Hits         6853     6871      +18     
- Misses       2177     2179       +2     

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[teutoburg]

See individual comments, but overall fine.