App startup insights in Benchmark

Early stage of the feature exposing app startup insights in
Macrobenchmark Studio output.

Bug: 353692849
Test: manual (experimental feature)
Change-Id: Iaeb5e40403aa4d7b9ad59e92b71e2c9abc9f0ca8

• benchmark/benchmark-common/src/main/java/androidx/benchmark/Insight.kt[Added - diff]
• benchmark/benchmark-common/src/main/java/androidx/benchmark/InstrumentationResults.kt[diff]
• benchmark/benchmark-macro-junit4/build.gradle[diff]
• benchmark/benchmark-macro-junit4/src/main/java/androidx/benchmark/macro/junit4/MacrobenchmarkRule.kt[diff]
• benchmark/benchmark-macro/src/androidTest/java/androidx/benchmark/macro/MacrobenchmarkTest.kt[diff]
• benchmark/benchmark-macro/src/main/java/androidx/benchmark/macro/InsightExtensions.kt[Added - diff]
• benchmark/benchmark-macro/src/main/java/androidx/benchmark/macro/Macrobenchmark.kt[diff]
• benchmark/benchmark-macro/src/main/java/androidx/benchmark/macro/MacrobenchmarkPhase.kt[diff]