Library autocomplete/suggest

With the new map, we should be able to suggest the names of all Overture libraries in a `LoadLibrary` call, i.e:

```luau
local Overture = require(path.to.Overture)

local library = Overture:LoadLibrary("<autocomplete suggest list>")
```

Within the `LoadLibrary` string, the user should be prompted with the names of all available libraries in their workspace.