Standardize RPC request and response objects

[t1m0thyj]

Currently there are some inconsistencies like fspath vs path below. We should try to use terms consistent with the z/OSMF APIs.

zowe-native-proto/packages/sdk/src/doc/zos-uss.ts

Lines 5 to 8 in d9cccae

	export interface Request extends IRpcRequest {
	command: "listFiles";
	fspath: string;
	}

zowe-native-proto/packages/sdk/src/doc/zos-uss.ts

Lines 17 to 21 in d9cccae

	export interface Request extends IRpcRequest {
	command: "readFile";
	path: string;
	encoding?: string;
	}