Summary:
This refactors some logic which sets up HMRClient in JS. The logic should live in RCTDevSettings, so it is shared in bridge/bridgeless mode.
This also means the logic will be compiled out when `RCT_DEV_MENU` is false.
Reviewed By: RSNara
Differential Revision: D19563629
fbshipit-source-id: 5c2553be9fd686a2a178f03bb5eed7a82cbadb1b