Refactor Exchanges Loading animation to include any number of exchanges

[jorgedclopes]

The current status of the system is that we have animation style elements for specific number of dexes. The problem is that if we have a number of dexes previously unaccounted for we'd have to add animations for these. The current implementation was done with urgency but it needs to be generalised to account for any number of dexes.

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[wixzi]

I can fix this to create dynamic styles based on dex size