Import assets raw and use .cache folder for things that need to be converted

[BrentFarris]

In an effort to remove duplicate raw asset files on the developer's machine, make it so that imported content is the raw file that was imported. To do this, the developer needs to be able to easily open the asset for editing in their default editor of choice.

This will be a little tricky with files like meshes, like glTF, because they need to remap texture paths and binary blobs to be relative to where those are stored (we will likely need to store the binary blob right next to the json). There are also lots of other mesh file formats that are all completely different from one another in output, which muddies the waters a bit.

• Change the mesh import to just copy the file in
• Create .cache folder in database for generated content data
• Check to see if the cache file is newer than the content, if not, regenerate it
• Change "Reimport" button in content workspace to "Reload"
• If .cache folder is missing, build cache at editor startup in background
• Add a helper function to know if a file's cache exists
  • This is needed for things like trying to spawn a mesh on the stage and it's cache hasn't yet been generated
• Add "Open in default editor" button in content workspace
• Add different editors binary paths to the editor settings workspace (same as code editor)

[BrentFarris]

I think I'm going to put this one on hold because meshes are a bit of a wild card. Most people will be editing in something like a .blend file that they will keep versions of. So storing raw .gltf or anything like that would be pointless as it's not their source content type.

That being said, I am adding an edit button so textures and other files can directly be edited from the content folder. That way developers can keep the raw source files they need and toss the ones they don't