weston-ini-conf: Rework to use fragments to construct weston.ini

weston-ini-conf: Rework to use fragments to construct weston.ini

Switch to constructing the weston.ini from fragments of files instead of
variables and variable flags.  This allows for much easier tracking of
signatures by leveraging existing mechanisms.  Update the Readme to
explain how to do the various operations with fragments as well.  Note
that for QEMU we do not need to pass -show-cursor as it's already
provided and we do want to change the VGA driver to one that reliably
provides DRM support.

For the HDMI connected screens, rather than name them by vendor name
them first for connection and then required transformation for correct
orientation.

For board-specific options, move them to the board directories.

When we need to change existing cfg options, rather than replace them
the proper location to do this in is the do_configure function.

Bug-AGL: SPEC-964
Change-Id: I2cceb4fd64f51eb2ab1d47419b77153cf02d7c12
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/11375
Reviewed-by: Stéphane Desneux <stephane.desneux@iot.bzh>
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>