framework/replay: Add argument to receive a JWT token as a file

Currently, piglit replay has the -j/--jwt argument to receive the token directly to access MinIO server. There is a use case where the JWT should not be exposed, where the token per se should not be shown in the command line. So giving a file path instead of the token is a better approach to avoid this leakage.

This commit adds --jwt-file argument as an alternative to -j/--jwt one. When the user gives this argument, piglit will open it and read the file content, treating it as the JWT token.