When togging Re-run, don't prompt about unreviewed tests

[brodieG]

In this cases, we have no changes, only unreviewed, should consider not prompting, particularly if it is a fast evaluation:

- New --------------------------------------------------------------------------

| The following test is new. Add test to store ([Y]es, [N]o, [P]rev, [B]rowse, 
| [R]erun, [Q]uit, [H]elp)?

> fun2a <- function(x) validate_args(x = setNames(character(3L), 
+     letters[1:3]) || matrix(0L, 3, 3) || NULL || list(character(), 
+     x = integer()))
> fun2a(letters[1:3])
Error in fun2a(x = letters[1:3]) : 
  For argument `x` at least one of these should pass:
  - `names(letters[1:3])` should be type "character" (is "NULL")
  - `letters[1:3]` should be matrix (is character)
  - `letters[1:3]` should be "NULL" (is "character")
  - `letters[1:3]` should be type "list" (is "character")

unitizer> R

| Toggling re-run mode ON for this unitizer

= Finalize Unitizer ============================================================

| You have 1 unreviewed tests; press `B` to browse tests, `U` to go to first 
| unreviewed test.

| You made no changes to the unitizer so there is no need to update it.  While 
| unnecessary, you can force an update by typing O at the prompt.

| Re-run unitizer ([Y]es, [P]rev, [B]rowse, [U]nreviewed, [R]erun, f[O]rce)?