Vite build process improvements

Moved token-bridge usdc-bridge mainnet testnet configs to different files to be consumed as imported typed vars
Created some new scripts to be able to run all variants
Added default "dev" and "start" scripts to use token-bridge testnet
Added a couple of utils needed to overload configs per variant
Fixed a couple of typos and a script using yarn instead of npm

XLabs / portal-bridge-ui