build(docs): add cmake target for docs

Description

Instead of testing doc builds in gtest, this PR moves docs builds to cmake.

Screenshot

Issues Fixed or Closed

Type of Change

[ ] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] Dependency update (updates to dependencies)
[ ] Documentation update (changes to documentation)
[x] Repository update (changes to repository files, e.g. .github/...)

Checklist

[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[ ] I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch must be updated before it can be merged. You must also Allow edits from maintainers.

[ ] I want maintainers to keep my branch updated

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 8.96%. Comparing base (13f94f1) to head (2f6aa6a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2748 +/- ## ====================================== Coverage 8.96% 8.96% ====================================== Files 94 94 Lines 17392 17392 Branches 8270 8270 ====================================== Hits 1560 1560 - Misses 12963 12967 +4 + Partials 2869 2865 -4 ``` | [Flag](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | Coverage Δ | | |---|---|---| | [Linux](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | `6.79% <ø> (ø)` | | | [Windows](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | `4.16% <ø> (ø)` | | | [macOS-12](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | `10.04% <ø> (-0.02%)` | :arrow_down: | | [macOS-13](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | `9.94% <ø> (-0.02%)` | :arrow_down: | | [macOS-14](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte) | `10.24% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte#carryforward-flags-in-the-pull-request-comment) to find out more. [see 3 files with indirect coverage changes](https://app.codecov.io/gh/LizardByte/Sunshine/pull/2748/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LizardByte)

LizardByte / Sunshine