tui: avoid deprecated import

[oliver-sanders]

• Respond to deprecation warning:

  DeprecationWarning: 'urwid.wimp' is not expected to be imported
  directly. Please use public access from "urwid" package. Module
  'urwid.wimp' is deprecated and will be removed in the future.
  from cylc.flow.tui.app import TuiApp

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• Applied any dependency changes to both setup.cfg (and conda-environment.yml if present).
• Tests are included (or explain why tests are not needed).
• CHANGES.md entry included if this is a change that can affect users
• Cylc-Doc pull request opened if required at cylc/cylc-doc/pull/XXXX.
• If this is a bug fix, PR should be raised against the relevant ?.?.x branch.

[wxtim]

Looks good.

[MetRonnie]

Got some other deprecation warnings too, don't know if you want to tackle them now or not

tests/integration/tui/test_app.py: 6 warnings
tests/integration/tui/test_mutations.py: 2 warnings
tests/integration/tui/test_show.py: 1 warning
tests/integration/tui/test_logs.py: 4 warnings
  ~/cylc-flow/cylc/flow/tui/app.py:279: PendingDeprecationWarning: AttrWrap is maintained for backwards compatibility only, new code should use AttrMap instead.
    footer = urwid.AttrWrap(urwid.Text(list_bindings()), 'foot')

tests/integration/tui/test_app.py: 6 warnings
tests/integration/tui/test_mutations.py: 2 warnings
tests/integration/tui/test_show.py: 1 warning
tests/integration/tui/test_logs.py: 4 warnings
  ~/cylc-flow/cylc/flow/tui/app.py:281: PendingDeprecationWarning: AttrWrap is maintained for backwards compatibility only, new code should use AttrMap instead.
    urwid.AttrWrap(self.listbox, 'body'),

tests/integration/tui/test_app.py: 6 warnings
tests/integration/tui/test_mutations.py: 2 warnings
tests/integration/tui/test_show.py: 1 warning
tests/integration/tui/test_logs.py: 4 warnings
  ~/cylc-flow/cylc/flow/tui/app.py:282: PendingDeprecationWarning: AttrWrap is maintained for backwards compatibility only, new code should use AttrMap instead.
    header=urwid.AttrWrap(header, 'head'),

tests/integration/tui/test_app.py: 211 warnings
tests/integration/tui/test_mutations.py: 41 warnings
tests/integration/tui/test_show.py: 19 warnings
tests/integration/tui/test_logs.py: 126 warnings
  ~/cylc-flow/cylc/flow/tui/app.py:94: DeprecationWarning: `TuiWidget.__super` was a deprecated feature for old python versions.Please use `super()` call instead.
    widget = self.get_indented_widget()

tests/integration/tui/test_app.py: 16 warnings
tests/integration/tui/test_mutations.py: 5 warnings
tests/integration/tui/test_show.py: 3 warnings
tests/integration/tui/test_logs.py: 15 warnings
  ~/cylc-flow/cylc/flow/tui/app.py:382: DeprecationWarning: Method `TreeListBox._set_body` is deprecated, please use property `TreeListBox.body`
    if self.update():

tests/integration/tui/test_app.py: 185 warnings
tests/integration/tui/test_mutations.py: 36 warnings
tests/integration/tui/test_show.py: 22 warnings
tests/integration/tui/test_logs.py: 101 warnings
  ~/.conda/envs/cylc8/lib/python3.10/site-packages/urwid/treetools.py:74: PendingDeprecationWarning: only for backwards compatibility. You should use the new standard container `contents`
    self._w.base_widget.widget_list[0] = [self.unexpanded_icon, self.expanded_icon][self.expanded]

tests/integration/tui/test_app.py: 185 warnings
tests/integration/tui/test_mutations.py: 36 warnings
tests/integration/tui/test_show.py: 22 warnings
tests/integration/tui/test_logs.py: 101 warnings
  ~/.conda/envs/cylc8/lib/python3.10/site-packages/urwid/widget/columns.py:150: PendingDeprecationWarning: only for backwards compatibility. You should use the new standard container `contents`
    self.widget_list = ml

tests/integration/tui/test_app.py: 31 warnings
tests/integration/tui/test_mutations.py: 7 warnings
tests/integration/tui/test_show.py: 2 warnings
tests/integration/tui/test_logs.py: 9 warnings
  ~/cylc-flow/tests/integration/tui/conftest.py:191: DeprecationWarning: Method `TreeListBox._set_body` is deprecated, please use property `TreeListBox.body`
    while not self.app.update():

tests/integration/tui/test_app.py: 22 warnings
tests/integration/tui/test_mutations.py: 11 warnings
tests/integration/tui/test_show.py: 6 warnings
tests/integration/tui/test_logs.py: 19 warnings
  ~/.conda/envs/cylc8/lib/python3.10/site-packages/urwid/listbox.py:1062: DeprecationWarning: `TuiWidget.__super` was a deprecated feature for old python versions.Please use `super()` call instead.
    key = focus_widget.keypress((maxcol,), key)

[oliver-sanders]

Wasn't planning on doing that right now.

[penguinolog]

Small too late comment (found this PR while looked up for deprecated imports usage):
from urwid import SelectableIcon should work the same for urwid versions released since 2010.
Technically from urwid import <Class> and from urwid import <CONSTANT> for 99% of API are stable (except totally deprecated hacks, which are planned to delete)