Squashes all the subpackages of `org.elasticsearch.rest.action` down to
the following:
* `o.e.rest.action.admin` - Administrative actions
* `o.e.rest.action.cat` - Actions that make tables for `grep`ing
* `o.e.rest.action.document` - Actions that act on documents
* `o.e.rest.action.ingest` - Actions that act on ingest pipelines
* `o.e.rest.action.search` - Actions that search
I'm tempted to merge `search` into `document` but the `document`
package feels fairly complete as is and `Suggest` isn't actually always
about documents either....
I'm also tempted to merge `ingest` into `admin.cluster` because the
latter contains the actions for dealing with stored scripts.
I've moved the `o.e.rest.action.support` into `o.e.rest.action`.
I've also added `package-info.java`s to all packges in `o.e.rest`. I
figure if the package is too small to deserve a `package-info.java` file
then it is too small to deserve to be a package....
Also fixes checkstyle in all moved classes.