feat(database): add command to list db properties

[kangasta]

Examples usage:

$ upctl db properties pg

 Property                              Create only   Type              Example                                              
───────────────────────────────────── ───────────── ───────────────── ──────────────────────────────────────────────────────
 admin_password                        yes           string or null    z66o9QXqKM                                           
 admin_username                        yes           string or null    avnadmin                                             
 automatic_utility_network_ip_filter   no            boolean                                                                
 autovacuum_analyze_scale_factor       no            number                                                                 
 autovacuum_analyze_threshold          no            integer                                                                
 autovacuum_freeze_max_age             no            integer           2e+08                                                
 autovacuum_max_workers                no            integer                                                                
 autovacuum_naptime                    no            integer                                                                

[...rest of the output omitted]

$ upctl db properties show --db=pg admin_username admin_password
  
  Key:          admin_username                                                                                                           
  Title:        Custom username for admin user. This must be set only when a new service is being created.                               
  Help message: Must consist of alpha-numeric characters, dots, underscores or dashes, may not start with dash or dot, max 64 characters 
  Create only:  yes                                                                                                                      
  Type:         string or null                                                                                                           
  Pattern:      ^[_A-Za-z0-9][-._A-Za-z0-9]{0,63}$                                                                                       
  Max length:   64                                                                                                                       
  
  Key:          admin_password                                                                                                        
  Title:        Custom password for admin user. Defaults to random string. This must be set only when a new service is being created. 
  Help message: Must consist of alpha-numeric characters, underscores or dashes                                                       
  Create only:  yes                                                                                                                   
  Type:         string or null                                                                                                        
  Pattern:      ^[a-zA-Z0-9-_]+$                                                                                                      
  Max length:   256                                                                                                                   
  Min length:   8