[LSL] Add support for a `.lslrc` file with aliases for includes

Luau already makes use of a .luaurc file and the plugin uses it's alias system in the slua require mechanism.

It would be nice to have a similar feature for LSL to make behavior between the two consistent and allow for include aliases to be stored with your project.

Proposed .lslrc format for now would only include the aliases section.

{
    "aliases": {
        "libs" : "D:\\secondlife\\lsl\\libraries",
        "my-lib" : "../../my-lib"
    }
}

Allowing for includes to follow a pattern like

#include "@libs/lib.lsl"
#include "@my-lib/my-lib.lsl"

Start by tracing the existing .luaurc alias handling and the plugin's slua require mechanism, then locate how LSL includes are resolved. Implement the proposed aliases-only .lslrc format and verify that @libs and @my-lib include paths resolve consistently with the examples.