Enable via:
./occ config:system:set core.login_flow_v2.allowed_user_agents 0 --value '/Custom Foo Client/i'
./occ config:system:set core.login_flow_v2.allowed_user_agents 1 --value '/Custom Bar Client/i'
if user agent string is unknown
the template with "Access forbidden"-"Please use original client" will be displayed
Signed-off-by: Misha M.-Kupriyanov <kupriyanov@strato.de>