Script that generates maven packages for a set of local files.

file_to_maven_package.gradle will create a local Maven repository
for packages that are not found in a set of remote Maven repositories
(currently Maven Central and Google Maven). Packages that are found
in the remote repositories are simply printed to the standard output.

Over half of the implementation is an indexer for Google Maven that
incrementally indexes the repository and stores the index in a local
JSON file. A cache of the index will eventually be hosted on github
and updated periodically to speed up the process of indexing the
repository.

The script exposes the top level tasks:
* install: Creates a local maven repo of supplied input libraries
  and looks for libraries in remote repos printing the results to
  the standard output.
* updateGoogleMavenIndex: Intended to be used from the resolver's
  build script to update the cached index on github.
* searchMavenIndexes: Searches indexed repositories for local
  artifacts by SHA-1 printing the matches to the standard output.

For example:

./gradlew \
  -b source/PlayServicesResolver/scripts/file_to_maven_package.gradle \
  -PTARGET_DIR=$(pwd)/tmp \
  -PGOOGLE_MAVEN_INDEX_URI=file://$(pwd)/unity-jar-resolver/index.zip \
  -PFILE_TO_MAVEN_PACKAGE="\
~/Downloads/flatbuffers-java-1.11.1.jar@\
com.google.flatbuffers:flatbuffers-java:0.0.0;\
source/PlayServicesResolver/scripts/download_artifacts_test_assets/\
m2repository/com/android/support/support-annotations/24.0.0/\
support-annotations-24.0.0.jar@\
com.android.support:support-annotations:24.0.0;\
source/PlayServicesResolver/scripts/download_artifacts_test_assets/\
m2repository/androidx/cursoradapter/cursoradapter/1.0.0/\
cursoradapter-1.0.0.aar@;\
source/PlayServicesResolver/scripts/download_artifacts_test_assets/\
m2repository/com/google/firebase/firebase-app-unity/4.3.0/\
firebase-app-unity-4.3.0.srcaar@" \
   install

Will read the cached Google Maven index file index.zip and incrementally
update it, create a local maven repo under "tmp" and print the following
output...

Packages:
org.psr:com.google.firebase.firebase-app-unity.4.3.0:0.0.0 file:/XXXX/unity-jar-resolver/tmp/
androidx.cursoradapter:cursoradapter:1.0.0 https://dl.google.com/dl/android/maven2/
com.android.support:support-annotations:24.0.0 https://dl.google.com/dl/android/maven2/
com.google.flatbuffers:flatbuffers-java:1.11.1 https://repo.maven.apache.org/maven2/

Bug: 135269831, 135273820
Change-Id: I6991a114480d8c76d4aeb160b83ac719c14bee55

Author: Stewart Miles