Add process.cwd()

[randomboi404]

It changes the following:

1. Uses a provider pattern so as to allow custom ProcessProvider for embedded systems where using the default StdProcessProvider will not be proper.

2. Adds process.cwd() so as to allow:

./boa
>> process.cwd()
"/root/boa"

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,862	52,862	0
Passed	49,471	49,471	0
Ignored	2,249	2,249	0
Failed	1,142	1,142	0
Panics	0	0	0
Conformance	93.59%	93.59%	0.00%

[codecov]

Codecov Report

❌ Patch coverage is 0% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.54%. Comparing base (6ddc2b4) to head (14a735e).
⚠️ Report is 644 commits behind head on main.

Files with missing lines	Patch %	Lines
core/runtime/src/process/mod.rs	0.00%	22 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4603      +/-   ##
==========================================
+ Coverage   47.24%   56.54%   +9.29%     
==========================================
  Files         476      548      +72     
  Lines       46892    60093   +13201     
==========================================
+ Hits        22154    33977   +11823     
- Misses      24738    26116    +1378     

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[jedel1043]

Implementation wise looks great! I just have an API suggestion and a comment on the error thrown when calling current_dir().

[jedel1043]

I would suggest just using impl IntoIterator<(JsString, JsString)> as the return value here, to mirror what std::env::vars() returns. IMO we really don't need a fallible method here.

[jedel1043]

It's not that useful to return an opaque error here; just use TypeError and pass e.to_string() as the message for the error, maybe with a nice error prefix to show that this error comes from calling std::env::current_dir()

[jedel1043]

By the way you can easily format nice error messages with our js_error macro:

js_error!(TypeError: "nice error message. source: {error}", e.to_string());