On change of map layer, save new layer to local storage

[ddrury]

• Added a name property to each layer object.
• Added leafletjs.baselayerchange() function to the map which when it fires saves the name property to local storage.
• On page load use the stored value to set the displayed layer.
• Tidy formatting in Bing maps module (unrelated to above)

[codecov]

Codecov Report

Merging #4165 (ed4e614) into main (64fe0e9) will decrease coverage by 0.02%.
The diff coverage is 30.00%.

@@             Coverage Diff              @@
##               main    #4165      +/-   ##
============================================
- Coverage     31.75%   31.73%   -0.03%     
+ Complexity    11119    11102      -17     
============================================
  Files          1106     1106              
  Lines         39106    39103       -3     
============================================
- Hits          12417    12408       -9     
- Misses        26689    26695       +6     

Impacted Files	Coverage Δ
app/Module/IndividualFactsTabModule.php	0.00% <0.00%> (ø)
app/Module/PlaceHierarchyListModule.php	0.00% <0.00%> (ø)
app/Statistics.php	93.66% <ø> (+0.29%)	⬆️
app/Statistics/Repository/MediaRepository.php	100.00% <ø> (ø)
app/Statistics/Google/ChartDistribution.php	45.00% <24.67%> (+3.03%)	⬆️
app/Module/IndividualListModule.php	50.50% <55.55%> (+0.12%)	⬆️
app/Statistics/Repository/PlaceRepository.php	98.98% <94.73%> (+10.61%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0125e23...ed4e614. Read the comment docs.

[ddrury]

See also #4727 and #4703

As this PR provides a method to save a users preferred map provider and layer to local storage it mitigates the problem whereby the default layer may change depending on how the map providers are enabled/disabled in the control panel, therefore the defaultLayer concept becomes redundant and the associated code can be removed.