Better error mesage for unset GIT parameters

[mgubaidullin]

If user did not set karavan.git.XXX parameters application should better managed situation and log it

	... 10 more
Caused by: io.quarkus.runtime.configuration.ConfigurationException: Failed to load config value of type class java.lang.String for: karavan.git.repository
		... 9 more
		at io.quarkus.arc.runtime.ConfigRecorder.validateConfigProperties(ConfigRecorder.java:60)
		at io.smallrye.config.inject.ConfigProducerUtil.getValue(ConfigProducerUtil.java:100)
		at io.smallrye.config.SmallRyeConfig.convertValue(SmallRyeConfig.java:371)
	Suppressed: java.util.NoSuchElementException: SRCFG00040: The config property karavan.git.repository is defined as the empty String ("") which the following Converter considered to be null: io.smallrye.config.Converters$BuiltInConverter
	... 7 more
	at io.quarkus.deployment.steps.ConfigBuildStep$validateConfigValues1665125174.deploy(Unknown Source)
	at io.quarkus.deployment.steps.ConfigBuildStep$validateConfigValues1665125174.deploy_0(Unknown Source)
	at io.quarkus.arc.runtime.ConfigRecorder.validateConfigProperties(ConfigRecorder.java:70)
Caused by: jakarta.enterprise.inject.spi.DeploymentException: io.quarkus.runtime.configuration.ConfigurationException: Failed to load config value of type class java.lang.String for: karavan.git.repository

better to wrap it with try...catch with giving a meaninful error message.

Originally posted by @vebera in #1164 (comment)