Support other kinds of searches in the Searchfox tool

We currently have find_function_definition, we should add:

• [ ] find_class_definition
• [ ] search_identifier
• [ ] calls_from
• [ ] calls_to
• [ ] calls_between

We should add the following parameters:

• [ ] Filter on JS only (.js, .mjs, .ts, .cjs, .jsx, .tsx)
• [ ] Filter on C/C++ only (.c, .cc, .cpp, .h, .hh, .hpp)
• [ ] Filter on WebIDL only (.webidl)
• [ ] Filter on a specific path
• [ ] Maximum depth