[MOB-3238] - Add missing install script in build.gradle

[Ayyanchira]

🔹 Jira Ticket(s) if any

https://iterable.atlassian.net/browse/MOB-3238

✏️ Description

This was removed in its last iteration during the clean up of bintray related files. But looks like we need it as part for performing ./gradlew install command.

NOTE:
This is the place from where gradle gets definition of install:
https://raw.githubusercontent.com/nuuneoi/JCenter/master/installv1.gradle
This task generates pom file.

Most of the content looks similar to our existing script in maven-push.gradle file, which also generates pom file.

[codecov]

Codecov Report

Merging #365 (67d86a8) into master (ffabfe7) will increase coverage by 0.13%.
The diff coverage is n/a.

❗ Current head 67d86a8 differs from pull request most recent head aa40a9e. Consider uploading reports for the commit aa40a9e to get more accurate results

@@            Coverage Diff             @@
##           master     #365      +/-   ##
==========================================
+ Coverage   67.32%   67.45%   +0.13%     
==========================================
  Files          61       61              
  Lines        3758     3758              
  Branches      438      438              
==========================================
+ Hits         2530     2535       +5     
+ Misses        966      961       -5     
  Partials      262      262              

Impacted Files	Coverage Δ
.../com/iterable/iterableapi/IterableRequestTask.java	81.85% <0.00%> (+2.21%)	⬆️

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