Enable truthy-bool checks in mypy and fix related warnings

[correctmost]

PR Description:

Docs: https://mypy.readthedocs.io/en/stable/error_code_list2.html#check-that-expression-is-not-implicitly-true-in-boolean-context-truthy-bool

Tests and Checks

• I have tested the code!

[correctmost]

Line 1011 already assumes self._disk_encryption is not None

[correctmost]

user.password is a Password object

[correctmost]

There is an earlier check on line 34

[correctmost]

self._help_window is always initialized:

archinstall/archinstall/tui/curses_menu.py

Lines 34 to 36 in 3df568d

	class AbstractCurses[ValueT](metaclass=ABCMeta):
	def __init__(self) -> None:
	self._help_window = self._set_help_viewport()

[correctmost]

MirrorMenu.run() always returns a MirrorConfiguration:

archinstall/archinstall/lib/mirrors.py

Lines 299 to 301 in 3df568d

	def run(self) -> MirrorConfiguration:
	super().run()
	return self._mirror_config

[correctmost]

_prompt_partition_fs_type does not allow skipping or resetting:

archinstall/archinstall/lib/disk/partitioning_menu.py

Lines 415 to 432 in 3df568d

	def _prompt_partition_fs_type(self, prompt: str | None = None) -> FilesystemType:
	fs_types = filter(lambda fs: fs != FilesystemType.Crypto_luks, FilesystemType)
	items = [MenuItem(fs.value, value=fs) for fs in fs_types]
	group = MenuItemGroup(items, sort_items=False)
	result = SelectMenu[FilesystemType](
	group,
	header=prompt,
	alignment=Alignment.CENTER,
	frame=FrameProperties.min(tr('Filesystem')),
	allow_skip=False,
	).run()
	match result.type_:
	case ResultType.Selection:
	return result.get_value()
	case _:
	raise ValueError('Unhandled result type')