…hen running in secure mode (#19238)

Fixes #19216
Follow-up #19175 

### Summary of the issue:

NVDA was failing to start on secure screens, unless the serviceDebug
global parameter was set.

### Description of user facing changes:

NVDA works on secure desktops again.

### Description of developer facing changes:

None

### Description of development approach:

The issue was caused by `utils._crashHandler.CrashStats.crashStatsPath`
assuming that `globalVars.appArgs.logFileName` would always represent a
path. Notwithstanding this, it also wrote to disk, even when
`NVDAState.shouldWriteToDisk` returned `False` (i.e. in scure mode or
running from the launcher).

1. Added several defensive measures to the new `utils._crashHandler`
module.
2. Changed `watchdog.initialize` to no longer add
`utils._crashHandler.crashHandler` as an unhandled exception filter when
running in secure mode.

### Testing strategy:

Ran from source, and executed the following in the python console to
ensure automatic restarts on crash still work as expected:

```py
import ctypes;ctypes.windll.kernel32.DebugBreak()
```

Modified NVDA to allow the scratchpad in secure mode, built a
self-signed launcher, and installed it.

Hit `alt+control+delete`, and observed that NVDA worked as expected.

Added the following global plugin to the scratchpad of the user and
system config:

```py
from globalPluginHandler import GlobalPlugin
import ctypes
from tones import beep
from core import postNvdaStartup

class GlobalPlugin(GlobalPlugin):
	def __init__(self):
		super().__init__()
		postNvdaStartup.register(self.crash)

	def crash(self):
		beep(500,100)
		ctypes.windll.kernel32.DebugBreak()
```

Restarted NVDA, and observed that it started, a tone was heard, and it
crashed, and this only happened 4 times.

Hit `alt+control+delete`, and observed that NVDA started, a tone was
heard, NVDA crashed, and did not restart.

### Known issues with pull request:

When NVDA crashes on the secure desktop, no feedback is given to the
user. However, this is not new.

Closes #19333

Fix-up of #19175.
Summary of the issue:

NVDA was crashing at startup when using --no-logging command line flag.
Description of user facing changes:

NVDA can start again when using the --nologging flag.
Description of developer facing changes:

N/A
Description of development approach:

When loading the crash list file, also test if its path is None since this is the case when using --no-logging flag.

Follow-up #19175

### Summary of the issue:

If NVDA crashes when running from source, git picks up
`nvda_crash_stats.txt` as an untracked file.

### Description of user facing changes:

None

### Description of developer facing changes:

Git will ignore `nvda_crash_stats.txt`, meaning it's much less likely to
be accidentally committed and doesn't clutter our git output.

### Description of development approach:

Added `source/nvda_crash_stats.txt` to `.gitignore`.

### Testing strategy:

Ran `git status`. Verified that `nvda_crash_stats` was no longer showing
as an untracked file.

### Known issues with pull request:

None