Enable more parts of AttributeLayoutTest because:
- partial Vulkan support for vertex data in client memory has landed
- we can work around bugs which prevented some parts from working
- we have more fine-grained control over which parts to run

Avoid glBufferSubData to work around ANGLE bug 2374.

Let subclasses decide about skipping test cases.  For example on Vulkan
indexed draw with vertex data in client memory is not supported yet.

BUG=angleproject:1683

Change-Id: Id073334299bd1a642b2518ccb3c47ebd8ff010d9
Reviewed-on: https://chromium-review.googlesource.com/933943Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>