Add an uninstall script (#21213)

Closes #14306

This looks at what #16660 did and install.sh script as a base for the
uninstall.sh script. The script is bundled with the cli by default
unless the cli/no-bundled-uninstall feature is selected which is done,
so package managers could build zed without bundling a useless feature
and increasing binary size.

I don't have capabilities to test this right now, so any help with that
is appreciated.

Release Notes:

- Added an uninstall script for Zed installations done via zed.dev. To
uninstall zed, run `zed --uninstall` via the CLI binary.

crates/cli/build.rs

@@ -0,0 +1,5 @@
+fn main() {
+    if std::env::var("ZED_UPDATE_EXPLANATION").is_ok() {
+        println!(r#"cargo:rustc-cfg=feature="no-bundled-uninstall""#);
+    }
+}