Implemented support for arrays in built-in function `len()`

[Luna-Klatzer]

What type of change does this PR perform?

• [ ] Info or documentation change (Non-breaking change that updates repo info files (e.g. README.md, CONTRIBUTING.md, etc.) or online documentation)
• [ ] Website (Change that changes the design or functionality of the websites or docs)
• [ ] Development or internal changes (These changes do not add new features or fix bugs, but update the code in other ways)
• [ ] Bug fix (Non-breaking change which fixes an issue)
• [x] New feature (Non-breaking change which adds functionality)
• [x] Breaking change (Major bug fix or feature that would cause existing functionality not to work as expected.)
• [ ] Requires a documentation update, as it changes language or compiler behaviour

Summary

Implemented support for arrays in built-in function len().

Closes #667

Detailed Changelog

Not present for website/docs changes

Added

• Support for internal type unions in built-in and internal functions. (#496)

Changed

• Argument type of built-in function print from str to any. (#667)

Does this PR create new warnings?

None.

Linked issues or PRs

• [x] #667

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 55.07246% with 31 lines in your changes missing coverage. Please review.

Project coverage is 83.88%. Comparing base (bb7dfd9) to head (18dc68f). Report is 5 commits behind head on dev-next.

Files	Patch %	Lines
...re/src/compiler/semantics/types/base/union-type.ts	28.57%	14 Missing and 1 partial :warning:
.../core/src/compiler/semantics/types/built-in/any.ts	30.00%	6 Missing and 1 partial :warning:
...core/src/compiler/semantics/types/built-in/func.ts	33.33%	4 Missing :warning:
...src/compiler/semantics/types/base/built-in-type.ts	80.00%	1 Missing and 1 partial :warning:
...ore/src/compiler/semantics/types/built-in/array.ts	66.66%	1 Missing and 1 partial :warning:
...rc/compiler/semantics/types/base/processed-type.ts	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev-next #680 +/- ## ============================================ - Coverage 84.00% 83.88% -0.13% ============================================ Files 270 271 +1 Lines 4514 4561 +47 Branches 481 491 +10 ============================================ + Hits 3792 3826 +34 - Misses 583 593 +10 - Partials 139 142 +3 ```

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