Allow both HMR clients and live reloading clients

[cpunion]

Explain the motivation for making this change. What existing problem does the pull request solve?

I almost preview on multi devices, sometimes I switch a device to HMR mode, and others are Live Reload mode, currently only the "HMR device" can update. I already used this patch a few months, and I think I'm not the only need it.

Prefer small pull requests. These are much easier to review and more likely to get merged. Make sure the PR does only one thing, otherwise please split it.

Very small :-)

Test plan (required)

Test Steps:

1. Open multi devices or emulators, switch one to HMR mode, and others are Live Reloading mode.
2. Update your code.

Expected result:

1. All devices can updated.
2. The "HMR device" only update with HOT RELOADING experience.

[facebook-github-bot]

By analyzing the blame information on this pull request, we identified @jeanlauliac and @davidaurelio to be potential reviewers.

[cpunion]

Aha, I forgot I created a pull request about this and it was closed.

See #6837

What's the status about that after a few months? can this be merged? I used it long time, but I must patch every version.

[lacker]

The comments are a bit odd, usually you don't want comments in the source code to refer to "this commit" because it's totally unclear what commit that's referring to.

Is there any behavior that gets degraded with this pull request?

Can you add a test to ensure this functionality continues to work? The reloading stuff seems to break a lot so we could really use better tests there.

[skevy]

Hi there!

The packager no longer lives in this repo. It now lives in https://github.com/facebook/metro-bundler. The reasoning for the split is explained here: #13976.

If you're still interested in pursuing changes to the packager for this PR, please open a PR on that repo! :)

Thanks!
-Adam