Remove copied proto src

[jasperpotts]

Removing copied protobuf sources, now clones hedera-protos repo during build. Depends on pull request #122

[nathanklick]

Need to actually use the hapiVersion property.

Suggested change

	gitRepositories {
	include("hedera-protobufs") {
	autoInclude.set(false)
	uri.set("https://github.com/hashgraph/hedera-protobufs.git")
	// optional, set what branch to use
	// branch.set("main")
	// you can also use a tag
	tag.set("v0.31.0")
	}
	}
	val hapiVersion by project
	gitRepositories {
	include("hedera-protobufs") {
	autoInclude.set(false)
	uri.set("https://github.com/hashgraph/hedera-protobufs.git")
	// optional, set what branch to use
	// branch.set("main")
	// you can also use a tag
	tag.set(hapiVersion)
	}
	}

[jasperpotts]

I cleaned up those, I could not us hapiVersion as seems like settings happens before properties file is loaded. So I updated comments in code and updated README explaining