4664: Moved CustomSelectorActivity to ViewBinding

[bosankus]

Fixes #4664

What changes did you make and why?

• Issue: As per the information provided and work request on the ticket above, CustomSelectorActivity.kt is currently using Kotlin Synthetic which creates auto-generated class, and has been alread deprecated.
• Solution: Hence migration was done by replacing kotlin-synthetic with viewbinding, which is always null safe, type-safe and supports both Java and Kotlin.

NB: During migration unnecessary ids of included layouts were removed from activity_custom_selector.xml which was showing error before the fix.

[bosankus]

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