Make implementation behave more like NodeJS net socket API

[jeanregisser]

This PR fixes issues observed in celo-org/celo-monorepo#1422

The main problem was react-native-tcp behaved slightly differently from the NodeJS net socket implementation and resulted in the initial write to the socket being lost while connecting on Android and failing on iOS.

• Fix unable to write while connecting on Android. NodeJS net socket allows writing while connecting. See https://github.com/nodejs/node/blob/96a65e85c59ab4a81f49f7088d9f4d270980c5b0/lib/net.js#L754-L764 Though iOS native implementation already supported write while connecting, it's now doing the logic in JS so it behaves the same and matches NodeJS implementation.
• Add writable property to support web3 rpc provider use case. See https://github.com/ethereum/web3.js/blob/4d57461fe8e9d26662d5a5afc9c03f38fb7a28be/packages/web3-providers-ipc/src/index.js#L208-L210
• Call undestroy on connect so closed or ended socket can be reused.
  This matches NodeJS implementation https://github.com/nodejs/node/blob/96a65e85c59ab4a81f49f7088d9f4d270980c5b0/lib/net.js#L233
• Make the origin of 'socket-X' log messages clearer

I'm sure there are other edge cases, but it currently works as expected for our usage.