gui-wm/labwc: Version bump 0.7.1 -> 0.7.2

[tfemby]

This commit does a few different things. The simplest being the version bump from 0.7.1 -> 0.7.2.

0.7.0 has been removed to keep the labwc dir tidy.

All of the builds were also not refreshing the icon cache upon merge so I've added in xdg_icon_cache_update into the pkg_postinst and pkg_postrm functions consequently.

The metadata.xml file also was missing the tags which I have now added.

[tfemby]

the syntax is broken for meson_feature

Using your suggestion, it should all be up to scratch now. Meson ebuilds aren't my strong suite but this has been a good learning experience!

[epsilon-0]

Thanks for the PR!