Remove volatility from schema manifest file

[erichaagdev]

The schema paths written to the schema manifest are full absolute paths. This introduces volatility in the build, makes it non-reproducible and non-relocatable, since the full absolute path to a schema will vary between machines, e.g., between a local user and a CI machine. An additional source of volatility is the timestamp written to the file which will vary between every invocation even on the same machine.

With this change, the schema paths written to the schema manifest are relativized to the base project directory. The relative path to a schema is all that's required locate it and will always be consistent between machines. Additionally, the java-ordered-properties library is used to ensure the properties file is always written in a deterministic order and removes the unnecessary timestamp.

[deweyjose]

Thanks for the contribution @erichaagdev! I'll take a look tonight and try to release in the coming days.

[chris-pirie]

Thanks so much for addressing this @erichaagdev! This is going to allow us to leverage build caching across over 500 of our repositories!! 😍

[erichaagdev]

@deweyjose I pushed one additional change. It occurred to me the schema-manifest.props file shouldn't even be written to the target sources directory to begin with. This additional change gives the file its own directory.