Interceptor

[tobiasKaminsky]

This adds possibility to add an interceptor to new OKHttpClient so that we can use pre-defined responses and do not have to use the server.

It is for now just a discussion.
I will open up a corresponding PR on files.

Ref: https://medium.com/ki-labs-engineering/an-easy-way-to-mock-an-api-response-using-retrofit-okhttp-and-interceptor-7968e1f0d050

[nextcloud-android-bot]

Lint

Type	master	PR
Warnings	2	2
Errors	0	0

SpotBugs (new)

Warning Type	Number
Bad practice Warnings	14
Correctness Warnings	38
Internationalization Warnings	6
Malicious code vulnerability Warnings	7
Multithreaded correctness Warnings	3
Performance Warnings	17
Security Warnings	1
Dodgy code Warnings	41
Total	127

SpotBugs (master)

Warning Type	Number
Bad practice Warnings	14
Correctness Warnings	38
Internationalization Warnings	6
Malicious code vulnerability Warnings	7
Multithreaded correctness Warnings	3
Performance Warnings	17
Security Warnings	1
Dodgy code Warnings	41
Total	127

[codecov]

Codecov Report

Merging #454 into master will decrease coverage by 0.00%.
The diff coverage is 38.46%.

@@            Coverage Diff             @@
##           master     #454      +/-   ##
==========================================
- Coverage   39.50%   39.50%   -0.01%     
==========================================
  Files         136      136              
  Lines        5895     5901       +6     
  Branches      771      773       +2     
==========================================
+ Hits         2329     2331       +2     
- Misses       3218     3222       +4     
  Partials      348      348              

Impacted Files	Coverage Δ
...loud/android/lib/common/OwnCloudClientFactory.java	12.50% <0.00%> (-0.71%)	⬇️
.../main/java/com/nextcloud/common/NextcloudClient.kt	50.00% <62.50%> (-2.46%)	⬇️
...wncloud/android/lib/resources/files/FileUtils.java	85.71% <0.00%> (+14.28%)	⬆️