feat: Looker SDK generator for the Dart language

[bryans99]

Description:

A generator for the Dart language. Note, only supports Looker SDK 4.0.

Changes:

1. Dart generator.
2. Tests for dart generator.
3. Generated dart methods and models.
4. Runtime library for dart.
5. Example dart implementation.
6. Dart unit tests,
7. Dart end to end tests.

[github-actions[bot]]

Codegen Tests

    1 files    18 suites   31s :stopwatch: 422 tests 408 :heavy_check_mark: 14 :zzz: 0 :x: 423 runs  409 :heavy_check_mark: 14 :zzz: 0 :x:

Results for commit 6e70e895.

[bryans99]

Converted to draft. google g3 reports a bunch of lint errors. Turned out I had missed turning on full lint. Have figured out how to do that but it will take a while to fix.

[github-actions[bot]]

Codegen Tests

    1 files    18 suites   26s :stopwatch: 422 tests 408 :heavy_check_mark: 14 :zzz: 0 :x: 423 runs  409 :heavy_check_mark: 14 :zzz: 0 :x:

Results for commit 83309aac.

[github-actions[bot]]

Codegen Tests

    1 files    18 suites   30s :stopwatch: 422 tests 408 :heavy_check_mark: 14 :zzz: 0 :x: 423 runs  409 :heavy_check_mark: 14 :zzz: 0 :x:

Results for commit 6d68297c.

[github-actions[bot]]

Codegen Tests

    1 files    18 suites   26s :stopwatch: 422 tests 408 :heavy_check_mark: 14 :zzz: 0 :x: 423 runs  409 :heavy_check_mark: 14 :zzz: 0 :x:

Results for commit 108aeef8.

[github-actions[bot]]

Codegen Tests

    1 files    18 suites   32s :stopwatch: 422 tests 408 :heavy_check_mark: 14 :zzz: 0 :x: 423 runs  409 :heavy_check_mark: 14 :zzz: 0 :x:

Results for commit 9f0a8f4f.

[neiljaywarner]

@bryans99 i'm interested in this if you have time to get back to it...