Fix, OptionsCreator: export options on Linux (#5774)

* Core/Utils: Use correct env for save_filename from AppImage

* OptionsCreator: run export on a separate thread

Running a blocking call from kivy misbehaves on Linux.
This also changes '*.yaml' to '.yaml' for Utils.save_filename,
which is the correct way to call it.

* Core/Utils: destroy Tk root after save/open_filename

This allows using those functions from multiple threads.
Note that pure Tk apps should not use those functions from Utils.

* OptionsCreator: show snack when save_filename fails

* OptionsCreator: disable window while exporting

* OptionsCreator: fixing typing of added stuff

typings/kivy/clock.pyi

@@ -0,0 +1,82 @@
+from _typeshed import Incomplete
+from kivy._clock import (
+    ClockEvent as ClockEvent,
+    ClockNotRunningError as ClockNotRunningError,
+    CyClockBase as CyClockBase,
+    CyClockBaseFree as CyClockBaseFree,
+    FreeClockEvent as FreeClockEvent,
+)
+
+__all__ = [
+    "Clock",
+    "ClockNotRunningError",
+    "ClockEvent",
+    "FreeClockEvent",
+    "CyClockBase",
+    "CyClockBaseFree",
+    "triggered",
+    "ClockBaseBehavior",
+    "ClockBaseInterruptBehavior",
+    "ClockBaseInterruptFreeBehavior",
+    "ClockBase",
+    "ClockBaseInterrupt",
+    "ClockBaseFreeInterruptAll",
+    "ClockBaseFreeInterruptOnly",
+    "mainthread",
+]
+
+class ClockBaseBehavior:
+    MIN_SLEEP: float
+    SLEEP_UNDERSHOOT: Incomplete
+    def __init__(self, async_lib: str = "asyncio", **kwargs) -> None: ...
+    def init_async_lib(self, lib) -> None: ...
+    @property
+    def frametime(self): ...
+    @property
+    def frames(self): ...
+    @property
+    def frames_displayed(self): ...
+    def usleep(self, microseconds) -> None: ...
+    def idle(self): ...
+    async def async_idle(self): ...
+    def tick(self) -> None: ...
+    async def async_tick(self) -> None: ...
+    def pre_idle(self) -> None: ...
+    def post_idle(self, ts, current): ...
+    def tick_draw(self) -> None: ...
+    def get_fps(self): ...
+    def get_rfps(self): ...
+    def get_time(self): ...
+    def get_boottime(self): ...
+    time: Incomplete
+    def handle_exception(self, e) -> None: ...
+
+class ClockBaseInterruptBehavior(ClockBaseBehavior):
+    interupt_next_only: bool
+    def __init__(self, interupt_next_only: bool = False, **kwargs) -> None: ...
+    def init_async_lib(self, lib) -> None: ...
+    def usleep(self, microseconds) -> None: ...
+    async def async_usleep(self, microseconds) -> None: ...
+    def on_schedule(self, event) -> None: ...
+    def idle(self): ...
+    async def async_idle(self): ...
+
+class ClockBaseInterruptFreeBehavior(ClockBaseInterruptBehavior):
+    def __init__(self, **kwargs) -> None: ...
+    def on_schedule(self, event): ...
+
+class ClockBase(ClockBaseBehavior, CyClockBase):
+    def __init__(self, **kwargs) -> None: ...
+    def usleep(self, microseconds) -> None: ...
+
+class ClockBaseInterrupt(ClockBaseInterruptBehavior, CyClockBase): ...
+class ClockBaseFreeInterruptAll(ClockBaseInterruptFreeBehavior, CyClockBaseFree): ...
+
+class ClockBaseFreeInterruptOnly(ClockBaseInterruptFreeBehavior, CyClockBaseFree):
+    def idle(self): ...
+    async def async_idle(self): ...
+
+def mainthread(func): ...
+def triggered(timeout: int = 0, interval: bool = False): ...
+
+Clock: ClockBase