chore(deps): Modernize some dependencies

[dpogue]

Platforms affected

iOS

Motivation and Context

This allows us to drop the fs-extra and unorm library by replacing their use with built-in NodeJS standard library calls.

Description

• Replace unorm module with String.prototype.normalize
• Replace fs-extra usage with equivalent NodeJS fs calls
• Upgrade which to latest version
• Use path.join in a bunch of spots where we're constructing paths
• Remove the (unused) nopt dependency

Testing

• [x] Existing unit tests pass
• [x] Created and built iOS test project

Checklist

• [x] I've run the tests to see all new and existing tests pass

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 86.56716% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 78.47%. Comparing base (1974dbb) to head (7ddec78).

Files	Patch %	Lines
lib/prepare.js	75.00%	3 Missing :warning:
lib/run.js	50.00%	3 Missing :warning:
lib/Api.js	75.00%	1 Missing :warning:
lib/build.js	85.71%	1 Missing :warning:
lib/plugman/pluginHandlers.js	92.85%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1413 +/- ## ========================================== - Coverage 78.50% 78.47% -0.03% ========================================== Files 16 16 Lines 1814 1812 -2 ========================================== - Hits 1424 1422 -2 Misses 390 390 ```

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