feat: Add a disabled configuration option for modules (#86)

• Add support for the disabled configuration option
This will allow you to selectively disable modules that you don't want or need. 😄
• Overwrite starship configuration file path with STARSHIP_CONFIG environment variable
• Write tests for the two configuration options that are available

src/modules/git_status.rs

@@ -17,7 +17,7 @@ use super::{Context, Module};
 ///   - `+` — A new file has been added to the staging area
 ///   - `»` — A renamed file has been added to the staging area
 ///   - `✘` — A file's deletion has been added to the staging area
-pub fn segment<'a>(context: &'a Context) -> Option<Module<'a>> {
+pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     // This is the order that the sections will appear in
     const GIT_STATUS_CONFLICTED: &str = "=";
     const GIT_STATUS_AHEAD: &str = "⇡";
@@ -35,7 +35,7 @@ pub fn segment<'a>(context: &'a Context) -> Option<Module<'a>> {
     let repository = Repository::open(repo_root).ok()?;
 
     let module_style = Color::Red.bold();
-    let mut module = context.new_module("git_status");
+    let mut module = context.new_module("git_status")?;
     module.get_prefix().set_value("[").set_style(module_style);
     module.get_suffix().set_value("] ").set_style(module_style);
     module.set_style(module_style);