Gets mandoline working on android

Gets mandoline working on android

This consists of the following pieces:
. html_viewer now uses ResourceProvider to get resources.
. html_viewer no longer directly uses java.
. The java support for mojo_runner/shell has been mode pluggable:
  . You specify the name of the .so to load by way of a meta-tag in
    the manifest. This way mandoline can specify it's own.
  . Android's main function calls to an InitContext() function that
    mandoline plugs in.
  . The apk can include resources to extract. These are listed in the
    file 'assets_list.' The gn template rule
    generate_mojo_shell_assets_list does this for you given a
    directory.
. Changed around scripts to work with both mojo_shell/runner and
  mandoline.

BUG=481698
TEST=covered by tests
R=ben@chromim.org, jcivelli@chromium.org

Review URL: https://codereview.chromium.org/1130763004

Cr-Commit-Position: refs/heads/master@{#329250}