Ensure that ArchiveHandle.getInputStream() cannot return null

Simplify ArchiveEntryInputStream.create() by using more modern Java
constructs. This makes the structure of this method more obvious.
Ensure that it cannot return a null value.
Mark the return type of this method as @NonNull.
Throw an IllegalArgumentException if the passed archive has an
unexpected type. Note that this condition can never happen with the
current implementation of ArchiveHandle.
Mark the return type of ArchiveHandle.getInputStream() as @NonNull.

This guaranteed non-null return value will simplify the implementation
of the upcoming UnpackJob class.

Bug: 406328303
Flag: EXEMPT no functional change with the current code
Test: atest DocumentsUIGoogleTests:com.android.documentsui.archives
Change-Id: Iefa02e7301b607b0d1396d9f84c5d979670b7d42