Make include paths relative to repository root

Having the include paths include the name of the repository root (e.g.
"gestures/include/gestures.h") causes issues when using the library in
other trees that can't name the root directory "gestures". Changing them
to be relative to the repository root (e.g. "include/gestures.h") avoids
that issue.

Except for the Makefile change, the edits were done using this command:

    sed --in-place 's|#include "gestures/|#include "|' src/** include/**

Then I also took the opportunity to sort the affected `#include` lines
where I noticed they were out of order.

BUG=b:251196347
TEST=build and run unit tests (cros_workon_make --test
     chromeos-base/gestures)

Change-Id: I208a05367616f341c7e69bceda7be896bb29b1f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/gestures/+/3966630
Tested-by: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Harry Cutts <hcutts@chromium.org>
108 files changed