Remove dependency to Spring Shell

This commit updates the samples to use Java's
standard CLI utilities instead of Spring Shell.

Resolves #1184

spring-statemachine-samples/spring-statemachine-samples.gradle

@@ -7,7 +7,6 @@ description = 'Spring State Machine Samples Common'
 dependencies {
 	management platform(project(":spring-statemachine-platform"))
 	implementation project(':spring-statemachine-core')
-	implementation 'org.springframework.shell:spring-shell-core'
 	implementation 'org.springframework.boot:spring-boot-starter'
 }