feat(installer): rewrite install script

- remove unused root packages.ini
- write config to yaml file
- allow to set public_url during install
- force icecast start right after package install
- move config file in place at the end of installation

BREAKING CHANGE: The bash installer has been rewritten, the flags and
options changed, please run `./install --help` to get more details.

legacy/install/logrotate/libretime-legacy.conf

@@ -1,5 +1,5 @@
-/var/log/libretime/legacy.log {
-  su www-data www-data
+@@LOG_DIR@@/legacy.log {
+  su @@USER@@ @@USER@@
   compress
   rotate 10
   size 1000k