fix(testing): e2e flag no longer needed, testID is now applicable in dev or prod builds

[canmertc]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• All existing tests are passing: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/DevelopmentWorkflow.md#running-unit-tests-application.
• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/tools/notes/WritingUnitTests.md.

What is the current behavior?

• It is not possible to test an accessibility-enabled app by using the same build. Currently, it needs to be passed --env.e2e that enables testID and blocks accessibility features before building for testing. Passing this argument is needed because View.setContentDescription method which is also used by TalkBack to announce items is also used in testID property's Android implementation to store the view identifier.
• Maestro (testing framework) is not able to select items by their id.

// Android

<Label text="My Button" testID="my-button" />

// not working
- assertVisible:
     id: "my-button"
     
// not working
- assertVisible:
     text: "My Button"
     
// working (but it shouldn't work this way)
- assertVisible:
     text: "my-button"
 
// working (but it shouldn't work this way)
- assertVisible: "my-button"

What is the new behavior?

• AccessibilityNodeInfo.setViewIdResourceName is used to set resource id instead of View.setContentDescription that sets content description on Android.
• No need to pass --env.e2e anymore. So the production builds can now be tested.
• accessibilityIdentifier will be the source of truth. Setting testID property will also set accessibilityIdentifier. But setting accessibilityIdentifier property will update testID only if there is a testID already set and has a different value.
• Maestro is now able to select items by their id and text

// Android

<Label text="My Button" testID="my-button" />

// working
- assertVisible:
     id: "my-button"
     
// working
- assertVisible:
     text: "My Button"
     
// working
- assertVisible:
     id: "my-button"
     text: "My Button"
 
// working
- assertVisible: "My Button"

[NathanWalker]

Brilliant work, thank you @canmertc