Use platform over appversion on global navigator object

[melton-jason]

This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

From Mozilla on appVersion: https://developer.mozilla.org/en-US/docs/Web/API/Navigator/appVersion

Recently, localization tests began failing because of an invalid setting of global.navigator:

https://github.com/specify/specify7/actions/runs/11707985658/job/32609369992

specify7/specifyweb/frontend/js_src/lib/tests/jsdom.js

Lines 10 to 14 in 7fe1b80

	global.navigator = {
	userAgent: 'node.js',
	appVersion: 'node.js',
	platform: 'node.js',
	};

This failing test was remedied in 76871c7, which functionally completely removed the reassignment of global.navigator.

However, it appears that support for navigator.appVersion has been dropped in some capacity, as navigator.appVersion was returning undefined:

https://github.com/specify/specify7/actions/runs/11726874323/job/32666586609

specify7/specifyweb/frontend/js_src/lib/components/Preferences/UserDefinitions.tsx

Lines 67 to 69 in 7fe1b80

	const altKeyName = globalThis.navigator?.appVersion.includes('Mac')
	? 'Option'
	: 'Alt';

This PR cleans up the code in the JSDOM configuration file, and uses navigator.platform instead of appVersion.

⚠️ Note that navigator.platform is itself deprecated: https://developer.mozilla.org/en-US/docs/Web/API/Navigator/platform

However, this use case is explicitly mentioned in the Mozilla docs, and may be a better alternative until a better solution is found...

But there is one case where, among the options you could use, navigator.platform may be the least-bad option: When you need to show users advice about whether the modifier key for keyboard shortcuts is the ⌘ command key (found on Apple systems) rather than the ⌃ control key (on non-Apple systems)

Checklist

• Self-review the PR after opening it to make sure the changes look good
  and self-explanatory (or properly documented)

[maxpatiiuk]

that should probably be done using mocking:

in beforeAll in some test file set userAgent/platform/...
in afterAll undo the change

[maxpatiiuk]

this is exactly the use case that was quoted by you from the MDN article, so probably using navigator.platform in the right choice in this case?