* Activate preview toolwindow on receiving preview configuration
* Don't show preview toolwindow until a preview is requested
* Add icon to preview toolwindow
* Replace usage of 'de.fuerstenau.buildconfig'
with a custom replacement, because the plugin
does not support Gradle 7.0+ and
there has not been any commit activity in 5 years
(https://github.com/mfuerstenau/gradle-buildconfig-plugin);
* Update 'com.github.johnrengelman.shadow' to 7.0.0
The build `0.4.0-build182` upgrades
`kotlinx-collections-immutable` library
(which is used by the compose runtime) to 0.3.4,
which was published to maven central,
so most usages of sunsetting jcenter repo
can be removed now.
Resolves#557