Validate Identifier string (MAC address) on Android

[avdyushin]

Describe the bug
A clear and concise description of what the bug is.

Currently on iOS we check if Identifier is a valid UUID (done automatically by NSUUID object).
However on Android we just use raw string value. We can check if it's a valid MAC address as well.

How to fix, some ideas from @Daeda88

private val regex = "^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$".toRegex()
fun main() {
    println("3D:F2:C9:A6:B3:4F".asValidIdentifier())
}

private fun String.asValidIdentifier(): String? = if (regex.matches(this)) {
    this
} else {
    null
}

or

private fun String.asValidIdentifier(): String? = regex.matchEntire(this)?.let {
    it.groupValues[0]
}

To Reproduce
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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
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Screenshots
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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
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