Fix #1139: Nominate uploaded image for deletion

[diddypod]

Description

Fixes #1139 Add Option to delete the uploaded image.

Added DeleteTask and added new functions to MediaWikiApi to make edits to the pages

Tests performed

Tested on Xiaomi (Wingtech) Redmi 2, with betaDebug.

Screenshots showing what changed

[nicolas-raoul]

Sounds reasonable, judging from the screenshots :-)
I guess needs for subsequent iterations will appear as users start to use the feature, but that's good for now I would say.

[codecov-io]

Codecov Report

Merging #1297 into master will decrease coverage by 0.08%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master   #1297      +/-   ##
=========================================
- Coverage    3.81%   3.73%   -0.09%     
=========================================
  Files         126     127       +1     
  Lines        5919    6054     +135     
  Branches      583     588       +5     
=========================================
  Hits          226     226              
- Misses       5678    5813     +135     
  Partials       15      15

Impacted Files	Coverage Δ
...rw/commons/mwapi/ApacheHttpClientMediaWikiApi.java	5.43% <0%> (-0.38%)	⬇️
...in/java/fr/free/nrw/commons/delete/DeleteTask.java	0% <0%> (ø)
...fr/free/nrw/commons/media/MediaDetailFragment.java	0% <0%> (ø)	⬆️

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[neslihanturan]

@diddypod Thanks for this great job. I think we should display "Succesfully nominated" message in more visible way, ie. with an alert.
Besides, @nicolas-raoul is it possible to get any information as "nominated for deletion" via MWAPI? If so we can prevent several nominations. If this is not technically possible, we can add this information to "Succesfully nominated" message, as "Succesfully nominated, please do not nominate this image again" (In more polite English)

[neslihanturan]

There is a notification for nomination process, so maybe we can recognize if an image is nominated for deletion.

[diddypod]

Okay @neslihanturan, I'll incorporate a check for that ASAP.

[diddypod]

Fixes issue: Potential multiple nominations

The AsyncTask now checks if the Commons:Deleion_Requests subpage exists to verify if the file has previously been nominated for deletion, and proceeds accordingly. Thus, each file may be nominated for deletion only once.
Also, the results of the nomination process are displayed as an alert, as @neslihanturan suggested, with an option to open the file page in the browser.

[neslihanturan]

Great @diddypod , very good job:) Will be testing this immediately

[neslihanturan]

@diddypod it works quite nice, thanks for your contribution. Maybe we can notify the user about "already nominated issue" before entering the message second time. What do you say?

But this can be a seperate PR, merging this one.