Fix WASM playground

[jedel1043]

This Pull Request fixes #2991.

It changes the following:

• Creates a new IdleModuleLoader that rejects all load requests.
• Makes IdleModuleLoader the default loader if SimpleModuleLoader returns a creation error.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,118	94,118	0
Passed	74,620	74,620	0
Ignored	17,750	17,750	0
Failed	1,748	1,748	0
Panics	0	0	0
Conformance	79.28%	79.28%	0.00%

[codecov]

Codecov Report

Merging #2992 (280060a) into main (9367ee2) will decrease coverage by 0.01%.
The diff coverage is 30.00%.

@@            Coverage Diff             @@
##             main    #2992      +/-   ##
==========================================
- Coverage   50.23%   50.22%   -0.01%     
==========================================
  Files         446      446              
  Lines       46000    46019      +19     
==========================================
+ Hits        23109    23115       +6     
- Misses      22891    22904      +13     

Impacted Files	Coverage Δ
boa_engine/src/module/mod.rs	2.79% <0.00%> (-0.11%)	⬇️
boa_wasm/src/lib.rs	0.00% <0.00%> (ø)
boa_engine/src/context/mod.rs	58.20% <66.66%> (+0.13%)	⬆️

... and 1 file with indirect coverage changes