[Jib CLI] set correct version and User-Agent

[chanseokoh]

Fixes #3149.

This will make Jib CLI use the version string as defined in jib-cli/gradle-properties for the User-Agent HTTP header and the output of $ jib --version.

Notes:

• Moves VersionInfo.java out of src/main/java into src/java-templates and converts it to a template.
• When compiling, it generates the final VersionInfo.java into build/generated-src while incorporating the version Gradle property into the template. The process is done with the Gradle Copy task.

I'm not sure if IntelliJ will require this, but you may need to run the :jib-cli:compileJava task once after re-configuring the project.

[codecov]

Codecov Report

Merging #3150 (73ecf6d) into master (5cfc9c8) will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #3150      +/-   ##
============================================
+ Coverage     71.08%   71.09%   +0.01%     
+ Complexity     2320     2319       -1     
============================================
  Files           280      279       -1     
  Lines          9825     9822       -3     
  Branches        992      992              
============================================
- Hits           6984     6983       -1     
+ Misses         2495     2493       -2     
  Partials        346      346              

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