Add comment injection support to remaining languages (#41710)

Release Notes:

- Added support for comment language injections for remaining built-in
languages and multi-line support for Rust

crates/languages/src/css/injections.scm

@@ -0,0 +1,3 @@
+((comment) @injection.content
+ (#set! injection.language "comment")
+)

crates/languages/src/diff/injections.scm

@@ -0,0 +1,2 @@
+((comment) @injection.content
+    (#set! injection.language "comment"))

crates/languages/src/jsonc/injections.scm

@@ -0,0 +1,2 @@
+((comment) @injection.content
+    (#set! injection.language "comment"))

crates/languages/src/rust/injections.scm

@@ -1,4 +1,7 @@
-((line_comment) @injection.content
+([
+    (line_comment)
+    (block_comment)
+] @injection.content
     (#set! injection.language "comment"))
 
 (macro_invocation