docs: Removing com.android.internal.* packages from Javadoc build

Several com.android.internal packages were being included in the
Javadoc build, even though they have no public APIs. Added a
package.html with the @hide tag to each of those packages, to
exclude them from the doc build.

Updated doc is staged to: http://go/dac-stage/reference/ ; verified
that the packages are now *not* in
http://go/dac-stage/reference/packages.html , and that package
summary files are not being generated for those packages.

Test: make ds-docs
Bug: 63166900
Change-Id: I7f96abb3e57d005c290cce6eda58f9368159a34e