Create dataset metadata schema

[mgallegos4]

Create dataset metadata schema and add functions to create and add the metadata file to the standard location.

May look something like this:

schema_version = "1.2"

[linux-debian]
version = "1.2.3"
format = "sqlite"
categories = ["linux"]

[nuget]
version = "1.2.3"
format = "sqlite"
categories = ["windows"]

or this:

{
"LinuxIncludes.db": {
"type": "cpp_headers",
"os": "linux",
"version": "1.2.9",
"last_updated":
}
}