weston: wrapper for weston modules argument

Due to custom option parser implementation weston accepts only one
argument of given type. As the result if multiple modules add --module
only last will be used. This fix introduces wrapper around modules in
terms of weston-init to prepare proper modules argument for weston and
moves systemd-notify module into weston-init module instead of command
line argument

Based on Poky revision #bdd30be1a3815f70062d8febca91eaf042a77c3d
Downstream changes: Adding add_weston_module function into weston-start
script and modify xwayland plugin to use new interface.

Submitted upstream:
https://lists.openembedded.org/g/openembedded-core/topic/patch_weston_wrapper_for/85453995
Ref: https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/issues/110



Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>