Add Options, Functions and Settings to convert Node-Names and Strings to kebab-case

- refactored and renamed String::_camelcase_to_underscore to String:_separate_compound_words
- refactored String::to_snake_case to work with the refactored String::_separate_compound_words
- created char_utils::is_hyphen to catch all hyphen variants in kebab-case conversion
- created String::to_kebab_case using the new String::_separate_compound_words
- created corresponding Documentation in String and StringName
- simplified both switch statements in EditorNode and ProjectDialog
- added new kebab-casing Option for Node Names in ProjectSettings
- added missing camelCase Options to Scene- and Node-Names in ProjectSettings
- simplified Mono RuntimeInterop Functions
- hooked up the ConnectionsDialog
- created additional Unit Tests

doc/classes/String.xml

@@ -1040,6 +1040,25 @@
 				[/codeblock]
 			</description>
 		</method>
+		<method name="to_kebab_case" qualifiers="const">
+			<return type="String" />
+			<description>
+				Returns the string converted to [code]kebab-case[/code].
+				[b]Note:[/b] Numbers followed by a [i]single[/i] letter are not separated in the conversion to keep some words (such as "2D") together.
+				[codeblocks]
+				[gdscript]
+				"Node2D".to_kebab_case()               # Returns "node-2d"
+				"2nd place".to_kebab_case()            # Returns "2-nd-place"
+				"Texture3DAssetFolder".to_kebab_case() # Returns "texture-3d-asset-folder"
+				[/gdscript]
+				[csharp]
+				"Node2D".ToKebabCase();               // Returns "node-2d"
+				"2nd place".ToKebabCase();            // Returns "2-nd-place"
+				"Texture3DAssetFolder".ToKebabCase(); // Returns "texture-3d-asset-folder"
+				[/csharp]
+				[/codeblocks]
+			</description>
+		</method>
 		<method name="to_lower" qualifiers="const">
 			<return type="String" />
 			<description>