ENT-6378 Migrate corda-shell to external repo (#7005)

Remove the shell code from the OS code base, this includes the modules:

- `:tools:shell`
- `:tools:shell-cli`

The shell will be run within a node if it exists within the node's `drivers` directory. 

This is done by using a `URLClassloader` to load the `InteractiveShell` class into Corda's JVM process and running `startShell` and `runLocalShell`.

Running the shell within the `:samples` will require adding:

```
cordaDriver "net.corda:corda-shell:<corda_shell_version>"
```

To the module's `build.gradle` containing `deployNodes`. The script will then include the shell in the created nodes.

testing/node-driver/build.gradle

@@ -27,6 +27,9 @@ sourceSets {
 dependencies {
     compile project(':test-utils')
 
+    compile group: 'org.apache.sshd', name: 'sshd-common', version: '2.3.0'
+//    integrationTestRuntime group: 'org.apache.sshd', name: 'sshd-common', version: '2.3.0'
+
     // Integration test helpers
     testCompile "org.assertj:assertj-core:$assertj_version"
     integrationTestImplementation "junit:junit:$junit_version"