Optional ability to query constant entity declarations

[gingerBill]

Optional ability to query constant entity declarations with information regarding their declaration location, type information, names, memory location, tag information.

This feature would be an opt-in feature and not available by default.

[gingerBill]

Package :: struct {
    name: string,
    files: []string,
    ...
}
Entity_Kind :: enum {
    Invalid,
    Type,
    Constant,
    Procedure,
}
Entity :: struct {
    kind: Entity_Kind,
    name: string,
    pkg: ^Package,
    location: runtime.Source_Code_Location,
    parent: ^Procedure,
    type: typeid,
    tags: []string,
    ...
}
Type :: struct {
    using entity: Entity,
}
Procedure :: struct {
    using entity: Entity,
    data: rawptr,
}
Constant :: struct {
    using entity: Entity,
}