
Get the UniTCM API base URL
get_base_url.RdChecks in order: (1) session value set via set_base_url(),
(2) option unitcm.base_url, (3) environment variable UNITCM_BASE_URL,
(4) hardcoded default.

get_base_url.RdChecks in order: (1) session value set via set_base_url(),
(2) option unitcm.base_url, (3) environment variable UNITCM_BASE_URL,
(4) hardcoded default.