Add begin/end/insert DebugUtilsLabel commands to SecondaryCommandBuffer.
Switch use of these commands to the outside renderpass command buffer
instead of directly in the primary command buffer.

This change should maintain the exact same sequence of commands but
avoids some direct use of the primary command buffer. This is
desirable for the threaded refactor where a worker thread will
process the SecondaryCommandBuffer into a primary and the main
thread will no longer use the primary command buffer directly.

Note that because the debug utils label has an arbitrarily long
string that we need to adjust the command allocation to allow for
the string size exceeding the default allocation size. In this case
we just make a single larger allocation to accommodate the command
with the large string.

Bug: b/154030403
Change-Id: Iab7832ffc3d38ce168da2d624bd5b5d5b33ec11b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2161955
Commit-Queue: Tobin Ehlis <tobine@google.com>
Reviewed-by: Charlie Lao <cclao@google.com>