* refactor: added toBZZbaseUnit function
* feat: added utility for attesting value is BZZ convertible to base units
* fix: conversion from 15 to 16 decimal places, added unsafe versions
* refactor: withdraw modal uses the safe conversion from BZZ
* refactor: added BigNumber and Token class to handle BZZ digits correctly
* refactor: extract deposit and withdraw functionality into single modal
* test: added tests for Token
* chore: removed unused component
* chore: addressed PR review, token decimal is now integer 0-18
* chore: added comment to clarify the value restriction on token amount
Vojtech Simetka