Fix navigation in the *Completions* buffer and enable more tests (bug#54374)

Fix navigation in the *Completions* buffer and enable more tests (bug#54374)

* lisp/ido.el: Use first-completion instead of next-completion.

* lisp/minibuffer.el (completion--insert): Put completion--string
text property on prefix and suffix as well.

* lisp/simple.el (first-completion, last-completion): New commands.
(next-completion): Rewrite to fix many bugs reported in
bug#54374, bug#55289, bug#55430.
(choose-completion): Use the text property completion--string that
allows to select a completion when point is on its prefix or suffix.
(switch-to-completions): Use first-completion instead of next-completion,
and last-completion instead of previous-completion.

* test/lisp/minibuffer-tests.el (completion-auto-select-test)
(completion-auto-wrap-test, completions-header-format-test)
(completions-affixation-navigation-test): Uncomment fixed lines.