fix(ios): TabGroup bar is wrongly transparent on iOS 15

[jquick-axway]

JIRA:
https://jira.appcelerator.org/browse/TIMOB-28505
https://jira.appcelerator.org/browse/TIMOB-28523

Summary:

• On iOS 15, the bottom tab bar in a tab group is completely transparent.
  • Should be translucent by default and show the color of tab window.
  • Prevented "tabsBackgroundColor" property from changing the bar color.
• Breaking-change on iOS 15 set "appearance" to transparent by default. Also requires us to set "scrollEdgeAppearance".

Tab Bar Translucency Test:

1. Create a Classic app project from template. (Provides tab bar icons.)
2. Use TabGroupColorWindowTest.js attached to TIMOB-28505 for the "app.js".
3. Build and run on iOS 15.
4. Verify bottom bar shows 3 tab titles/icons and is green as shown in the iOS 14 screenshot in TIMOB-28505.
5. Tap on tab 2 and verify the "red" window shows through the bottom tab bar.
6. Tap on tab 3 and verify the "blue" window shows through the bottom tab bar.

Tab Bar Color Test:

1. Create a Classic app project from template. (Provides tab bar icons.)
2. Use TabGroupColorSharedTest.js attached to TIMOB-28505 for the "app.js".
3. Build and run on iOS 15.
4. Verify bottom tab bar's background is light-green.
5. Tap on tab 2 and 3 and verify tab bar's background is still light-green.

[build]

	Fails
🚫	Tests have failed, see below for more information.

	Messages
📖	✊ The commits in this PR match our conventions! Feel free to Rebase and Merge this PR when ready.
📖	❌ 1 tests have failed There are 1 tests failing and 955 skipped out of 16915 total tests.
📖	💾 Here's the generated SDK zipfile.

Tests:

Classname	Name	Time	Error
ios.ipad.Titanium.Filesystem.File	.remoteBackup assigning Boolean value doesn't throw (14.4.0)	2.063	Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (app.js) run@file:///Users/build/Library/Developer/CoreSimulator/Devices/8004FEFB-9C69-45DD-8F64-47B0C61BCF24/data/Containers/Bundle/Application/5DDEF462-87FD-4511-8AFD-D0EACC89E206/mocha.app/ti.main.js:9258:22 processImmediateQueue@file:///Users/build/Library/Developer/CoreSimulator/Devices/8004FEFB-9C69-45DD-8F64-47B0C61BCF24/data/Containers/Bundle/Application/5DDEF462-87FD-4511-8AFD-D0EACC89E206/mocha.app/ti.main.js:9321:18 drainQueues@file:///Users/build/Library/Developer/CoreSimulator/Devices/8004FEFB-9C69-45DD-8F64-47B0C61BCF24/data/Containers/Bundle/Application/5DDEF462-87FD-4511-8AFD-D0EACC89E206/mocha.app/ti.main.js:9298:52

Generated by 🚫 dangerJS against 2c1f140

[jquick-axway]

Closing since Apple fixed this issue as of Xcode 13 beta 3.

[jquick-axway]

Re-opening this PR since the issue came back when testing it with Xcode 13 beta 5.

[garymathews]

CR: PASS

[ewanharris]

FR Pass. TabGroup bar is now displayed as it was on iOS 14