feat: Themes support +2 new themes blue and gold.

[psprint]

Description

I thought it would be good to support different color themes.

Motivation and Context

The function +zinit-message allows easy theming via the col-file, etc. ZINIT hash fields. I've extracted the block of code that assigns them into a separate file share/themes/default.zsh and added two new files: …/blue.zsh with a new, different blue shades color setting and …/gold.zsh, different gold shades color setting.

Related Issue(s)

Usage examples

ZITHEME=blue
…… sourcing of zinit.zsh ……

With gold theme:

With blue theme:

How Has This Been Tested?

Types of changes

• 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 change)

Checklist:

• [] My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[psprint]

@vladdoster ping? or maye I could be added to the project so that I could commit? I would do it via PRs like you and wait for reviews, just shorter than it is currently