refactor: share language IDs with indentation configuration

src/ruby.rs

@@ -1006,7 +1006,7 @@ mod tests {
             r#"
 Vamp.configure do |c|
   c.tab_spaces = 4
-  c.language_tab_spaces = { "Ruby" => 2, "Makefile" => nil, "JSON" => 1, "YAML" => 255 }
+  c.language_tab_spaces = { "ruby" => 2, "makefile" => nil, "json" => 1, "yaml" => 255, "cpp" => 3, "typescriptreact" => 5 }
 end
 "#,
         );
@@ -1021,6 +1021,8 @@ end
             ("plain.txt", "", "    "),
             ("buffer.json", "", " "),
             ("buffer.yaml", "", widest.as_str()),
+            ("buffer.cpp", "", "   "),
+            ("buffer.tsx", "", "     "),
         ] {
             let source = format!("{prefix}αx\nβy");
             let path = fixture.file(name, &source);
@@ -1066,7 +1068,7 @@ end
         for value in ["0", "-1", "256", "1.5", "true", r#""4""#, "[]", "{}"] {
             for assignment in [
                 format!("c.tab_spaces = {value}"),
-                format!(r#"c.language_tab_spaces = {{ "Ruby" => {value} }}"#),
+                format!(r#"c.language_tab_spaces = {{ "ruby" => {value} }}"#),
             ] {
                 let config = fixture.file(
                     "config.rb",
@@ -1079,7 +1081,7 @@ end
             "nil",
             "[]",
             r#"{ "" => 2 }"#,
-            r#"{ :Ruby => 2 }"#,
+            r#"{ :ruby => 2 }"#,
             r#"{ "\n" => 2 }"#,
         ] {
             let config = fixture.file(