Add code mode to Text Search

[madebyisaacr]

Add support for "code" mode to the Text Search plugin, and enable the Cmd+Shift+F shortcut in the code editor. In code mode, it will only search code files, enabling it to be used as a global search tool for code in your project.

The ... menu and ability to enable/disable certain asset types will be hidden in code mode, as the only searchable type here is code.