Ship with Java 8 bytecode

[Guardiola31337]

Description

Ship with Java 8 bytecode

• I have added any issue links
• I have added all related labels (bug, feature, new API(s), SEMVER, etc.)
• I have added the appropriate milestone and project boards

Goal

Unblock us from taking advantage of some Java 8 language features #2787 (comment)

Worth mentioning that currently mapbox-java adds it implicitly from Retrofit mapbox/mapbox-java#1127 https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-270-2019-12-09 https://cashapp.github.io/2019-02-05/okhttp-3-13-requires-android-5 Refs. mapbox/mapbox-java#1095 mapbox/mapbox-java#1127 and #2684

Also added recently to the UI SDK

mapbox-navigation-android/libnavigation-ui/build.gradle

Lines 48 to 51 in 7435256

	compileOptions {
	sourceCompatibility JavaVersion.VERSION_1_8
	targetCompatibility JavaVersion.VERSION_1_8
	}

Implementation

Add

compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
}

to all modules and

plugins.withId('org.jetbrains.kotlin.jvm') {
  compileKotlin {
    kotlinOptions {
      jvmTarget = "1.8"
    }
  }
}

to root's build.gradle file under subprojects.

Testing

• I have tested locally (including SNAPSHOT upstream dependencies if needed) through testapp/demo app and run all activities to avoid regressions
• I have tested via a test drive, or a simulation/mock location app
• New and existing unit tests pass locally with my changes

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have updated the CHANGELOG including this PR

cc @mapbox/navigation-android

[codecov-commenter]

Codecov Report

Merging #3003 into master will decrease coverage by 0.00%.
The diff coverage is 12.50%.

@@             Coverage Diff              @@
##             master    #3003      +/-   ##
============================================
- Coverage     36.78%   36.78%   -0.01%     
  Complexity     2216     2216              
============================================
  Files           554      554              
  Lines         19953    19956       +3     
  Branches       1885     1885              
============================================
  Hits           7340     7340              
- Misses        11776    11779       +3     
  Partials        837      837              

[kmadsen]

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The future is now! 🎂

[zugaldia]