[Java][FlightRPC] FlightServer builder should store File, not InputStream

[lidavidm]

Describe the bug, including details regarding any error messages, version, and platform.

Methods like useTls and useMTlsClientVerification should store a File instead of opening the file immediately, then at build time we can open the file and make sure to close the input stream (as required by Netty). This minimizes the logic in the builder setters. Followup for apache/arrow#38461

Component(s)

FlightRPC, Java

[rtadepalli]

take