Allow async as identifier name in certain contexts

[jedel1043]

Just a small change in the parser to fix a couple of tests related to async as an identifier name.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,657	94,657	0
Passed	73,901	73,905	+4
Ignored	17,505	17,505	0
Failed	3,251	3,247	-4
Panics	0	0	0
Conformance	78.07%	78.08%	+0.00%

Fixed tests (4):

test/language/expressions/async-arrow-function/escaped-async-line-terminator.js [strict mode] (previously Failed)
test/language/expressions/async-arrow-function/escaped-async-line-terminator.js (previously Failed)
test/language/statements/for-await-of/head-lhs-async.js [strict mode] (previously Failed)
test/language/statements/for-await-of/head-lhs-async.js (previously Failed)

[codecov]

Codecov Report

Merging #2936 (214eb32) into main (ba7d216) will increase coverage by 0.00%.
The diff coverage is 16.66%.

@@           Coverage Diff           @@
##             main    #2936   +/-   ##
=======================================
  Coverage   52.09%   52.09%           
=======================================
  Files         435      435           
  Lines       43713    43709    -4     
=======================================
- Hits        22771    22770    -1     
+ Misses      20942    20939    -3     

Impacted Files	Coverage Δ
boa_parser/src/parser/expression/assignment/mod.rs	79.33% <0.00%> (ø)
boa_parser/src/parser/statement/expression/mod.rs	27.27% <0.00%> (ø)
...er/src/parser/statement/iteration/for_statement.rs	56.93% <0.00%> (ø)
boa_parser/src/parser/statement/mod.rs	61.31% <0.00%> (ø)
boa_parser/src/parser/expression/primary/mod.rs	54.04% <100.00%> (+0.33%)	⬆️

[HalidOdat]

Looks good to me!