feat(payment): add more payment channels than just email and phone (think: chat)

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Part of #40845

cc @ruthra-kumar

This implements an appropriate payment channel (not email or phone), which is implemented by one of the target gateways (e.g. whatsapp link or app-/push-notification-based).

None of the current channels is suitable for that business logic.

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Fears are nothing more than a state of mind. - Napoleon Hill

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_{Kindly help move this PR forward. Many thanks from Yours Sincerely!}

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What the caterpillar calls the end of the world, the master calls a butterfly. - Richard Bach

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_{Kindly help move this PR forward. Many thanks from Yours Sincerely!}

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Watch your thoughts, they become your words Watch your words, they become your actions Watch your actions, they become your habits Watch your habits, they become your character Watch your character, it becomes your destiny. -

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_{Kindly help move this PR forward. Many thanks from Yours Sincerely!}