Swap: Clear source input amount when changing source asset

[GrassRootsCrypto]

When changing the source asset after putting in the amount, the amount is not reset.

e.g. Swapping 500 RUNE to LTC, if the source asset is changed from RUNE to BTC then the swap quote will be 500 BTC to LTC even though the wallet does not have 500 BTC.

If the source asset is changed, the source asset should reset to 0.

[GrassRootsCrypto]

Swapping input amount from RUNE to BTC
Also it is beyond my Max amount in the wallet