Add convenience methods to ModuleLoader

[jedel1043]

While implementing an example of async module fetching, I realized it would be useful to have a way to insert a module through a &dyn ModuleLoader. This PR provides that API.

Drafting because I'm still experimenting with the final design of the API.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,108	94,108	0
Passed	74,644	74,644	0
Ignored	17,740	17,740	0
Failed	1,724	1,724	0
Panics	0	0	0
Conformance	79.32%	79.32%	0.00%

[codecov]

Codecov Report

Merging #3007 (e34edbc) into main (6879c59) will increase coverage by 0.36%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #3007      +/-   ##
==========================================
+ Coverage   50.22%   50.58%   +0.36%     
==========================================
  Files         446      446              
  Lines       46048    45923     -125     
==========================================
+ Hits        23127    23230     +103     
+ Misses      22921    22693     -228     

Impacted Files	Coverage Δ
boa_engine/src/module/mod.rs	2.75% <0.00%> (-0.04%)	⬇️
boa_examples/src/bin/modules.rs	0.00% <ø> (ø)

... and 46 files with indirect coverage changes

[jedel1043]

Yeah, I think this should be enough for now. We can revisit the API if we have reports about its limitations in the future.

[HalidOdat]

Looks good to me! :)