Add delete-shared-domain command

Admins can use this command to delete shared domains they had previous
created with `cf create-shared-domain`

[Finishes #64525874]
Remove create-domain TIP referencing map-domain
Add wildcard=true for backwards-compatible domain creation

[Finishes #64525818, #64525840]

Signed-off-by: Max Brunsfeld <mbrunsfeld@pivotallabs.com>