Extract Prisma support into an extension (#9820)

This PR extracts Prisma support into an extension and removes the
built-in Prisma support from Zed.

Release Notes:

- Removed built-in support for Prisma, in favor of making it available
as an extension. The Prisma extension will be suggested for download
when you open a `.prisma` file.

crates/extensions_ui/src/extension_suggest.rs

@@ -38,6 +38,7 @@ pub fn suggested_extension(file_extension_or_name: &str) -> Option<Arc<str>> {
                 ("latex", "tex"),
                 ("make", "Makefile"),
                 ("nix", "nix"),
+                ("prisma", "prisma"),
                 ("r", "r"),
                 ("r", "R"),
                 ("sql", "sql"),