Added new custom option for color config, marked themes folder as deprecated.

[peppidesu]

#749: when color: custom is specified, lsd will look for $XDG/lsd/colors.yaml and load the theme. The old custom theme behaviour is marked as deprecated and will show a warning when used.

• Renamed ThemeOption::Custom to ThemeOption::CustomLegacy
• Added new ThemeOption::Custom

---

TODO

• Use cargo fmt
• Add necessary tests
• Add changelog entry
• Update default config/theme in README (if applicable)
• Update man page at lsd/doc/lsd.md (if applicable)

[muniu-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: peppidesu

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov-commenter]

Codecov Report

Merging #851 (fd28652) into master (2fe3fcd) will decrease coverage by 0.02%.
The diff coverage is 76.47%.

❗ Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

@@            Coverage Diff             @@
##           master     #851      +/-   ##
==========================================
- Coverage   86.48%   86.46%   -0.02%     
==========================================
  Files          49       49              
  Lines        4602     4610       +8     
==========================================
+ Hits         3980     3986       +6     
- Misses        622      624       +2     

Impacted Files	Coverage Δ
src/flags/color.rs	92.24% <50.00%> (-0.81%)	⬇️
src/color.rs	50.80% <84.61%> (+1.35%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more