This patch enables end users to configure external plugins in the spire-server config. Unsupported internal plugins are not able to be set. --------- Signed-off-by: Kevin Fox <[email protected]> Signed-off-by: kfox1111 <[email protected]> Co-authored-by: Edwin Buck <[email protected]> Co-authored-by: Faisal Memon <[email protected]>