Implements Uploader protocol in MediaCoordinator and PostCoordinator.

[diegoreymendez]

Fixes #11785
Fixes #11784

Implements the Uploader protocol in both coordinator, and wires it so that it's triggered when the App is opened, when it comes to foreground, and when Reachability detects there's a connection.

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

Known Issues / Scope limitations:

Reachability isn't working very well, but from my investigation this is not related to my PR. Reachability is simply failing to call the closures it should call.

I'll need to investigate this separately, as it goes beyond the scope of this specific PR.

Testing:

Test 1:

1. Create a post with media while offline.
2. Put the app in the background.
3. Go back online.
4. Bring the app back to foreground.
5. Make sure the post is uploaded.

Test 2:

1. Create a post with media while offline.
2. Close the App.
3. Go back online
4. Launch the app again.
5. Make sure the post is uploaded.

[peril-wordpress-mobile]

	Warnings
⚠️	PR is not assigned to a milestone.

Generated by 🚫 dangerJS

[yaelirub]

Hey @diegoreymendez, wonderful work here!
Test 1:
The media upload resumed when the app returned to foreground but the image overlay stayed.

Test 2:
The media upload resumes when the app was relaunched but the image was never attached to the post and only a placeholder is visible.

This seem to happen only in Aztec. Gutenberg works

[yaelirub]

Reachability isn't working very well, but from my investigation this is not related to my PR. Reachability is simply failing to call the closures it should call.

Diego, have you looked into using NWPathMonitor from Apple's Network framework?

[diegoreymendez]

Diego, have you looked into using NWPathMonitor from Apple's Network framework?

Only available in iOS 12 or newer, which makes it a no-go :(

One other option is probably this but I'd like to keep that as a separate task since I think fixing reachability is beyond the scope of this specific PR.

I've opened this issue for it: #11840

[diegoreymendez]

@yaelirub - Awesome feedback... I've opened a new issue to tackle that problem separately here: #11846.

I've decided to split it because it's going to be easier for me to make progress on this incrementally, and because this issue is only present in the feature branch.

Rest assured we'll make sure everything is working before merging the feature branch.

Thanks for the review!

[yaelirub]

Should this be a weak self?

[diegoreymendez]

Yep. Will submit a PR to fix.