refactor formatAmount

[yuetloo]

Need to refactor formatAmount https://github.com/clrfund/monorepo/blob/develop/vue-app/src/utils/amounts.ts#L4 by breaking it down into different functions to handle separately input as string, FixedNumber, BigNumber, max decimal and significant digits.

• need to remove the code that could convert big number to unsafe javascript number.
• various places also call this function with hardcoded token decimal of 18