Added extensions settings where information on extensions can be found and bookmarklet is generated

Created arg modifier dialog to assist in editing youtube-dl args
- This arg dialog contains all the available args and their description
- Includes a convenient search bar and categorized list of args to help you find the one you're looking for, or just explore what's available.

Arg modifier is available for both global args (in settings) and local args (in the advanced mode)

src/app/main/main.component.css

@@ -119,4 +119,9 @@ mat-form-field.mat-form-field {
 
 .advanced-input {
     width: 100%;
+}
+
+.edit-button {
+    margin-left: 10px;
+    top: -5px;
 }