Add Mariana Theme (#1097)

This theme is a port of the default Mariana and Breakers theme in
Sublime Text 4 (closes #642). This also comes with a variant based of
off the [Mariana Pro Warm](https://arc.net/l/quote/erujorqf) Vscode
Theme.


### Preview:
<table>
  <tr>
<td rowspan="2"><img
src="https://github.com/bIaqat/mariana-theme-zed/raw/main/assets/mariana.png"
width="500"></td>
<td><img
src="https://github.com/bIaqat/mariana-theme-zed/raw/main/assets/mariana-breakers.png"
width="250"></td>
  </tr>
  <tr>
<td><img
src="https://github.com/bIaqat/mariana-theme-zed/raw/main/assets/mariana-trench.png"
width="250"></td>
  </tr>
</table>

.gitmodules

@@ -422,6 +422,10 @@
 	path = extensions/make
 	url = https://github.com/caius/zed-make.git
 
+[submodule "extensions/mariana-theme"]
+	path = extensions/mariana-theme
+	url = https://github.com/biaqat/mariana-theme-zed.git
+
 [submodule "extensions/marine-dark"]
 	path = extensions/marine-dark
 	url = https://github.com/MarineDark/marine-dark.zed.git

extensions.toml

@@ -493,6 +493,10 @@ version = "0.0.8"
 submodule = "extensions/make"
 version = "1.0.1"
 
+[mariana-theme]
+submodule = "extensions/mariana-theme"
+version = "0.5.0"
+
 [marine-dark]
 submodule = "extensions/marine-dark"
 version = "1.0.0"