RUM-713 Allow customer to use non standard obfuscation

[xgouchet]

What does this PR do?

Adds a nonDefaultObfuscation option in the extension for our plugin. This will create an uploadTask even if the Android minifyEnabled option is false

Motivation

Among others, Dexguard users are not using Android's minifyEnabled which relies on the default R8/Proguard obfuscation. For those users, the upload task wasn't created even on variants using DexGuard who needed it.

Fixes #132

Usage

datadog {
    nonDefaultObfuscation = true
    mappingFilePath = "custom/path/to/mapping.txt"
}

[codecov-commenter]

Codecov Report

Merging #199 (5e2931f) into develop (288840c) will decrease coverage by 0.03%. The diff coverage is 88.89%.

@@              Coverage Diff              @@
##             develop     #199      +/-   ##
=============================================
- Coverage      86.08%   86.05%   -0.03%     
- Complexity       177      181       +4     
=============================================
  Files             21       21              
  Lines            582      588       +6     
  Branches          76       78       +2     
=============================================
+ Hits             501      506       +5     
- Misses            53       55       +2     
+ Partials          28       27       -1     

Files	Coverage Δ
.../datadog/gradle/plugin/DdExtensionConfiguration.kt	100.00% <100.00%> (ø)
...com/datadog/gradle/plugin/DdAndroidGradlePlugin.kt	74.38% <87.50%> (+0.02%)	:arrow_up: