Uniswap and Transak Integrations

This MR intends to provide a new UX flow to the token sales process.

It integrates Transak modal to buy Minds tokens with Fiat currency and Uniswap modal to buy Minds tokens with cryptocurrency

Steps to test

• Click on 'Buy Tokens' on the left navigation panel
• Connect to your wallet provider
• Choose a payment method
• Accept sales terms
• Click continue
• Close modal
• Click on 'Earn' on the left navigation panel
• Click pool option