Switch to OKHttp

[seadowg]

Closes #2869

What has been done to verify that this works as intended?

Tests run locally and a quick play with the app on the emulator. Also ran the build through test lab as a precaution.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

This should not effect users at all but as we're changing the backbone of the communication with Open Rosa servers it would be good to check Collect thoroughly against Aggregate/Central (and any other common Open Rosa servers).

Before submitting this PR, please make sure you have:

• run ./gradlew checkAll and confirmed all checks still pass OR confirm CircleCI build passes and run ./gradlew connectedDebugAndroidTest locally.
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines

[seadowg]

Ooooohhhh. Went to do one last commit to clean out the HttpClientConnection itself and it seems like we're still using the httpclientandroidlib dependency for the ContentType object.

I'll have a look at moving this out as I think it's best we don't leave the custom lib lying around.

[seadowg]

Ok this looks good for testing now. Had to rework the CollectThenSystemContentTypeMapper somewhat so that stops that having to be saved for a rainy day!

[lognaturel]

The rationale for the while loop was presumably that since it's user input there could be multiple trailing /, as unlikely as that might seem. Did you change it because it just doesn't seem likely or is there another reason?

[seadowg]

Nope that is a genuine mistake. I can look at putting that back in and make sure it's covered by a test so it doesn't get absentmindedly removed again by someone (like me).

[lognaturel]

For a rainy day / good first issue, some of the types that Collect matches against are handled by the Android type mapper. It would be great for someone to go through and remove custom handling for those, I think.

[kkrawczyk123]

I believe that tested with success here!
Verified on Androids: 4.2, 4.4, 5.1, 6.0, 7.0 and 8.1

List of verified cases:

• Aggregate 2.0 download and send
• Central download and send
• Autosend Aggregate 2.0 and Central
• 1000 submissions send to Aggregate
• 1000 submissions send to Central
• 1000 submissions send to Google sheet
• Ona download and send
• Ona autosend
• Kobo download and send
• Kobo autosend
• Send the form with specified submission URL
• Aggregate 1.7 download, send and autosend
• Automatically download the upgraded version of the form
• Download form from Google Drive
• Send to Google Sheet
• Autosend to Google Sheet
• Autosend specified in form

@opendatakit-bot unlabel "needs testing"
@opendatakit-bot label "behavior verified"

[lognaturel]

Thank you, @seadowg and @kkrawczyk123! Great to see httpclientandroidlib go.

@yanokwa, please see odk-x/httpclientandroidlib#2 which can be merged when the release goes out.