OIDC connector: Allow specifying empty prompt type (#3373)

Enhanced the OIDC connector to allow specifying an empty promptType parameter. Previously, the default behavior always appended 'consent' if promptType was not specified. This adjustment was necessary due to variations in default behaviors across certain Identity Providers (IDPs).

Signed-off-by: m.nabokikh <maksim.nabokikh@flant.com>
Signed-off-by: Maksim Nabokikh <maksim.nabokikh@flant.com>