Wrap BaseIdent name_override_opt & TraitName in an Arc

[JoshuaBatty]

Description

I generated a flame graph and saw that we are spending a ton of time cloning BaseIdent and TraitName. I've wrapped the name_override_opt in BaseIdent with an Arc and also changed TraitName to:

type TraitName = Arc<CallPath<TraitSuffix>>;

Again running the same test being used in #5976 and also incorporating that PR's optimisations for the benchmark, we are getting a further 33.47% performance increase.

Before: Elapsed time: 22.02603425s
After: Elapsed time: 14.653166459s

In discussions with Jibril today, we should probably look at implementing a String interning system but this can be addressed in a future PR.

[github-actions]

Benchmark for 0448ab5

Click to view benchmark

Test	Base	PR	%
code_action	5.6±0.10ms	5.4±0.10ms	-3.57%
code_lens	300.5±9.76ns	288.3±8.68ns	-4.06%
compile	6.7±0.08s	3.9±0.05s	-41.79%
completion	5.1±0.03ms	4.7±0.01ms	-7.84%
did_change_with_caching	6.1±0.04s	3.4±0.04s	-44.26%
document_symbol	957.3±16.36µs	977.2±30.66µs	+2.08%
format	87.6±1.68ms	90.4±1.28ms	+3.20%
goto_definition	343.3±9.09µs	368.3±7.64µs	+7.28%
highlight	9.1±0.14ms	9.0±0.17ms	-1.10%
hover	621.2±8.36µs	486.9±4.06µs	-21.62%
idents_at_position	118.6±0.65µs	122.6±1.19µs	+3.37%
inlay_hints	653.4±9.43µs	665.4±22.74µs	+1.84%
on_enter	511.8±22.42ns	482.2±15.24ns	-5.78%
parent_decl_at_position	3.7±0.04ms	3.7±0.03ms	0.00%
prepare_rename	345.8±10.35µs	367.8±6.67µs	+6.36%
rename	9.6±0.03ms	9.6±0.19ms	0.00%
semantic_tokens	1066.6±14.07µs	1066.1±64.91µs	-0.05%
token_at_position	339.3±2.87µs	357.4±2.16µs	+5.33%
tokens_at_position	3.7±0.02ms	3.7±0.03ms	0.00%
tokens_for_file	417.8±4.17µs	424.1±1.88µs	+1.51%
traverse	51.1±2.00ms	40.2±1.09ms	-21.33%

[github-actions]

Benchmark for 54725e9

Click to view benchmark

Test	Base	PR	%
code_action	5.5±0.12ms	5.4±0.09ms	-1.82%
code_lens	291.3±8.50ns	289.2±8.52ns	-0.72%
compile	6.8±0.13s	4.0±0.03s	-41.18%
completion	5.0±0.15ms	4.7±0.09ms	-6.00%
did_change_with_caching	6.2±0.08s	3.5±0.06s	-43.55%
document_symbol	954.8±24.33µs	1002.8±46.17µs	+5.03%
format	87.6±1.43ms	89.8±0.53ms	+2.51%
goto_definition	352.6±5.98µs	373.4±6.17µs	+5.90%
highlight	9.2±0.19ms	9.0±0.02ms	-2.17%
hover	586.2±7.11µs	496.0±6.17µs	-15.39%
idents_at_position	119.3±0.46µs	123.9±1.01µs	+3.86%
inlay_hints	642.2±19.20µs	672.2±17.26µs	+4.67%
on_enter	495.9±13.86ns	485.5±19.95ns	-2.10%
parent_decl_at_position	3.7±0.03ms	3.7±0.04ms	0.00%
prepare_rename	348.2±7.76µs	365.1±5.53µs	+4.85%
rename	9.7±0.13ms	9.6±0.12ms	-1.03%
semantic_tokens	1048.4±26.45µs	1046.4±19.65µs	-0.19%
token_at_position	345.6±2.28µs	368.5±2.41µs	+6.63%
tokens_at_position	3.7±0.13ms	3.8±0.14ms	+2.70%
tokens_for_file	433.4±3.71µs	418.6±2.04µs	-3.41%
traverse	51.2±1.32ms	40.9±1.07ms	-20.12%