Replace flushAndGetPrimaryCommandBuffer() function with
endRenderPassAndGetCommandBuffer() for events and queries. The end
result should be the same, but this allows a number of places that were
putting commands directly into the primary to put the commands into
ANGLE's custom SecondaryCommandBuffer (SCB) instead.

This also fixes a couple of minor bugs related to command buffer
ordering. flushAndBeginRenderPass() now flushes any outside
RenderPass (RP) commands first. Also, when insideRP commands are
flushed to the primary, set "mHasPrimaryCommands = true;"

Bug: b/153666475
Change-Id: I68413f25d27175afed0a20bc49f22f4c8d01e4fb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2156932Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Charlie Lao <cclao@google.com>
Commit-Queue: Tobin Ehlis <tobine@google.com>