feat(milestone): milestone tables, views, forms and one selection model

milestone view printed the list row, and milestone list hid the due date
and progress. milestone list now shows ID TITLE [STATE] DUE PROGRESS, open
milestones first and by due date; milestone view shows the state, due
date, progress, description and the milestone's web page (also --web).

Every milestone command addresses milestones by title or ID. Mutations
report ✓ lines: milestone create also prints the new milestone's URL and
takes the title as an argument; close and reopen skip milestones already
in that state; delete names the milestone in its confirmation; milestone
issue add and remove report one line such as "✓ Added #1, #2 to
milestone "v1.0" in alice/x". milestone issue list uses the issue table.
milestone edit without flags on a terminal opens the milestone form with
the current values, and every milestone command completes milestone
titles and has help text with examples.

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

internal/app/app_test.go

@@ -424,16 +424,6 @@ const (
 	issue attachment list
 	issue attachment upload
 	issue attachment view
-	milestone close
-	milestone create
-	milestone delete
-	milestone edit
-	milestone issue add
-	milestone issue list
-	milestone issue remove
-	milestone list
-	milestone reopen
-	milestone view
 	pr attachment delete
 	pr attachment download
 	pr attachment edit
@@ -449,8 +439,6 @@ const (
 `
 	longsToWrite = `
 	issue attachment
-	milestone
-	milestone issue
 	pr attachment
 	time
 `