fix(android): allow requestLegacyExternalStorage attribute

[garymathews]

• Add requestLegacyExternalStorage to attributes

JIRA Ticket

Test:

1. Create a Classic Titanium project.
2. Add the below <application/> element to the project's "tiapp.xml" file.
3. Build for Android.
4. In Finder (or Windows Explorer) go to project folder: ./build/android
5. Open the "AndroidManifest.xml" file.
6. Verify that the <application/> element has attribute android:requestLegacyExternalStorage="true".

<?xml version="1.0" encoding="UTF-8"?>
<ti:app xmlns:ti="http://ti.appcelerator.org">
	<android xmlns:android="http://schemas.android.com/apk/res/android">
		<manifest>
			<application android:requestLegacyExternalStorage="true"/>
		</manifest>
	</android>
</ti:app>

[build]

	Messages
📖	💾 Here's the generated SDK zipfile.
📖	✅ All tests are passing Nice one! All 4334 tests are passing. (There are 471 tests skipped)
📖	✊ The commits in this PR match our conventions! Feel free to Rebase and Merge this PR when ready.

Generated by 🚫 dangerJS against ec6209c

[jquick-axway]

CR: Pass

[keerthi1032]

FR passed.LegacyExternalStorage attribute is added.

Test Environment:
Name = Mac OS X
Version = 10.14.6
Architecture = 64bit
Node.js
Node.js Version = 10.16.2
npm Version = 6.9.0
Titanium CLI
CLI Version = 5.2.1
Titanium SDK
SDK Version =Local sdk 8.3.0.v20190909124736
Device -Samsung s5 android 6
Emulator- pixel android q, pixel 3xl android 8