Inspired by #1640, this change cleans up the logic used when
reading in secrets files, provides clearer warnings when the
secrets files can't be parsed, and adds tests for those methods.
Signed-off-by: Adam Leff <adam@leff.co>
only load plugins through the binary, never through the library. This avoids issue we have in accidentally loading plugins in tests and integration work. They should only be loaded when users request them.