Add `.spec.proxySecretRef.name` to the `GitRepository` API to allow
referencing a secret containing the proxy settings to be used for all
remote Git operations for the particular `GitRepository` object.
It takes precedence over any proxy configured through enviornment
variables.
Signed-off-by: Sanskar Jaiswal <jaiswalsanskar078@gmail.com>
Consumers still relying on this should make use of `v1beta2` to
facilitate any transition.
In addition, remove the `*Implementation` constants for now removed
Git implemenations.
Signed-off-by: Hidde Beydals <hidde@hhh.computer>