Also fix action functions to support being ivy-called without
exiting the completion session.

* counsel.el (counsel-kmacro-kill): Try to prevent being called
outside of counsel-kmacro minibuffer completion.
(counsel-kmacro): Fix docstring.  Ensure kmacro.el is loaded before
evaluating any variables it defines.  Remove kmacro-counter from
prompt; it is already listed per-kmacro in ring.  Do not default to
kmacro-initial-counter-value; defer to kmacro-specific counter.
Reword docs and action labels to avoid confusion between
kmacro-initial-counter-value and kmacro-counter.
(counsel--kmacro-format-function): Simplify.
(counsel--with-kmacro): New macro for destructuring a kmacro object.
(counsel--format-kmacro): New function.
(counsel--kmacro-candidates): Use it and counsel--with-kmacro to
format kmacro ring objects.  Use kmacro-ring-head.  Fix stale
edmacro-fix-menu-commands warning message.  Clarify docstring.
(counsel--kmacro-exec): New compatibility shim for
kmacro-exec-ring-item.
(counsel-kmacro-action-run): Improve docstring.  Fix
current-prefix-arg usage and let ivy-current-prefix-arg override it.
Use counsel--kmacro-exec.  Update ivy-last for non-exiting ivy-call.
(counsel-kmacro-action-delete-kmacro): Check whether candidate is in
kmacro-ring before deleting, instead of comparing to last-kbd-macro.
Use kmacro-delete-ring-head.  Update ivy-last state for ivy-call.
(counsel-kmacro-action-copy-initial-counter-value)
(counsel-kmacro-action-copy-counter-format-for-new-macro): Use
counsel--with-kmacro for slot access.  Clarify docstrings.
(counsel--kmacro-cycle-until): New function.
(counsel-kmacro-action-cycle-ring-to-macro): Use it for bounded ring
cycling.  Update ivy-last for non-exiting ivy-call.
(counsel-kmacro-action-set-saved-starting-counter): Clarify
docstring.  Avoid having to construct a kmacro object directly by
cycling ring, reading new counter, and cycling back.  Use
read-number.  Update ivy-last state for ivy-call.
(counsel-kmacro-action-execute-after-prompt): Improve docstring.
Fix current-prefix-arg usage and let ivy-current-prefix-arg override
it.  Use read-number, read-string, and format-prompt.  Avoid kmacro
destructuring via counsel--kmacro-exec.

Fixes #3066.