removed unused code (#3919)

internal/build/archive.go

internal/build/download.go

internal/build/env.go

internal/build/pgp.go

internal/build/util.go

internal/jsre/completion.go

internal/jsre/completion_test.go

internal/jsre/deps/bignumber.js

internal/jsre/deps/bindata.go

internal/jsre/deps/deps.go

internal/jsre/deps/web3.js

internal/jsre/jsre.go

internal/jsre/jsre_test.go

internal/jsre/pretty.go

internal/utesting/utesting.go

internal/utesting/utesting_test.go

internal/web3ext/bor_ext.go

internal/web3ext/web3ext.go