Add Zig item

[TheFunctionalGuy]

Description

This PR adds support for a Zig prompt item.

Note: I was unsure whether I needed to update the tide_pwd_markers variable.

How Has This Been Tested

I have added a test case that contains 3 test cases:

1. Being in a directory without a build.zig file should result in no item
2. Being in a directory with a build.zig and zig version 0.11.0 should result in a prompt like: ZIG_LOGO 0.11.0
3. Being in a directory with a build.zig and zig version 0.12.0-dev.789+e6590fea1 should result in a prompt like: ZIG_LOGO 0.12.0-dev so you know that your current version is a dev build

• I have tested using Linux.
• I have tested using MacOS. (I have no access to a Mac so I cannot test this)

Checklist

• I am ready to update the wiki accordingly.
• I have updated the tests accordingly.

[IlanCosman]

Thank you for the fantastic PR. You nailed pretty much everything, down to the minute details!

[TheFunctionalGuy]

Thank you. Am I allowed to update the Wiki? Because it says: not yet updated for v6.

[IlanCosman]

Yes, please do! Much appreciated :)

[TheFunctionalGuy]

Done. :)