ZSS Unix contents API untagged file GET behavior unexpected

[1000TurquoisePogs]

When a file is untagged, most programs in USS assume the contents are 1047.
However, some files can be binary instead.
So, there's fairly common behavior of what files are readable and are not in an editor when untagged.

But not in the Zowe Desktop editor. It does something more interesting, but unexpected
When untagged, it reads through a list of extensions to determine if the file should be treated as 1047 or binary.

https://github.com/zowe/zowe-common-c/blob/ed8ae5f9794179da06102c13970081d308e09543/c/httpserver.c#L3856-L3897

That mime list has multiple uses, beyond just the unix contents api. But we're using it for that at least, and maybe we shouldn't?
There are two issues with it currently

1. there is no .txt, .java, .ts extensions listed... we need to target more common cases at least
2. when a file has no extension, it is assumed binary, which is opinionated

For the unix api, it seems like there should be an option to turn the extension-behavior on/off, or to provide a custom list.