Build linux sample with musl

- Change sample build to use musl on linux
- Optionally remove version from jar so that
  e2e tests don't need to use version in path.
- Add better matrix to e2e so that we're able to
  build on one OS and then test with others.
- Fixes #576

spring-shell-samples/spring-shell-samples.gradle

@@ -18,8 +18,22 @@ springBoot {
 	buildInfo()
 }
 
+if (project.hasProperty('springShellSampleE2E') && springShellSampleE2E.toBoolean()) {
+	bootJar {
+	   	archiveName = "$baseName.$extension"
+	}
+}
+
 graalvmNative {
 	metadataRepository {
 		enabled = true
 	}
+	binaries {
+		main {
+			if (project.hasProperty('springShellSampleMusl') && springShellSampleMusl.toBoolean()) {
+				buildArgs.add('--static')
+				buildArgs.add('--libc=musl')
+			}
+		}
+	}
 }