fix(admin): offer --purge for users who own repositories and show roles

admin user delete of a user who owns repositories failed with Gitea's raw
HTTP 422. The error now says what blocks the deletion and how to proceed,
and --purge deletes the account with its repositories, packages and
organization memberships after typing the username on a terminal.

admin user list shows ROLE and STATUS columns (admin, restricted, user;
active, inactive, login prohibited) with the email and creation date
instead of admin=true/active=true cells, and --query filters by username,
name or email. admin user view shows the account instead of its list
row. create asks for a missing username and email address with readable
labels and re-asks for invalid answers, mutations print ✓ lines, usernames
complete, and every command has examples.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/app_test.go

@@ -422,11 +422,6 @@ const (
 	pr review cancel-request
 `
 	examplesToWrite = `
-	admin user create
-	admin user delete
-	admin user edit
-	admin user list
-	admin user view
 	alias delete
 	alias list
 	alias set
@@ -604,8 +599,6 @@ const (
 	workflow view
 `
 	longsToWrite = `
-	admin
-	admin user
 	alias
 	auth
 	branch