be9a13c Add configuration/argument testing (MeshCollider)
Pull request description:
Adds a new functional test for testing various command line and configuration file argument interactions, that aren't specific enough to other functionality to be placed in other tests.
Currently this tests the error messages for non-existent datadir, which would have caught the bug fixed in https://github.com/bitcoin/bitcoin/pull/11829. It also tests that command line arguments override the ones in the config file.
I plan on working on a fix for https://github.com/bitcoin/bitcoin/issues/11819 / https://github.com/bitcoin/bitcoin/issues/1044 and then expanding this test with cases for that.
Tree-SHA512: 97aea18c67d331db3ca3d0c99c79267cf012df67fddafc9fac63d392f5c3a6469aa14d93b5865c3bbe561461648d2485367978a77446483b8df53d1916f1c8e8
