Link commands

[nluaces]

Command set for links:

• link ~export~ generate new
• link udpate
• link delete
• link status

Fixes #1560

[nluaces]

Changes made based on feedback received aboutlink export

• rename to link generate
• don't generate a file, print the output with the resources
• remove spinner
• remove tls-secret flag shortcut t
• remove arguments: link name and output file
• only check if the tls-secret name was specified if the generation of credentials is disabled
• the link name will be generated by the command (link-[SITE NAME])
• if the credentials are going to be generated by the command, the tls secret name will have the same value as the link name by default (link-[SITE NAME])
• improvements in the text showed in the help
• remove the certificate resource after printing the output