Modify local installation to use kyma-installer

[pbochynski]

Local installation script should build kyma-installer from sources based on current installer image.

To do:

• adapt local installation based on released installer -> @strekm -> PR Local installation on kyma installer #1182

• adapt local installation based on released installer (windows scripts) -> @crabtree -> PR Change PS scripts to use kyma-installer image #1351

• adapt installation based on installer build locally -> @jakkab -> PR Adapt local installation based on installer build to use Kyma-installer #1202

• create generic script that concatenates provided yaml files. AC: The script returns pretty-printed combo yaml to stdout-> @jakkab -> PR Add concat-yamls.sh script #1249

• document local development (explain how kyma-installer works, how scripts work and so on) -> @strekm

• switch local installation to use local combo yaml -> @jakkab -> PR switch local installation to combo yaml #1285

• fix cluster installation to use installer (bug introduced by changing installer.yaml deployment to use kyma-installer) -> @crabtree -> PR Fix cluster installation with kyma-installer #1215

[strekm]

in context of local development release of kyma-installer is not needed. local kyma-installer is being built on the fly. We should mention in documentation that local installation is installation under the development.