Adds schema registry's truststore and keystore settings

[andsel]

Release notes

Add schema registry's setting for keystore and truststore.

What does this PR do?

This commit mainly exposes location password and type settings for schema registry's secret and key stores. It brings those configuration options, if available, and directly forward down to the Kafka's SerDes library and Manticore client. Introduces a script named setup_keystore_and_truststore.sh to setup keystore and truststore used in integration tests. Furthermore it reworks a little bit the bash scripts to setup Kafka and Schema Registry in integration test to avoid download of artifacts if they are already locally downloaded.

Why is it important/What is the impact to the user?

With this PR the user is able to configure trust and key stores to be used to connect and interact specifically with Schema Registry. These stores are different from the one configured for the Kafka client.

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• [x] I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• [x] setup schema registry with separate keystore, import the certificate into client's truststore and verify that it can the plugin can connect to it running a pipeline.

How to test this PR locally

To test this PR a couple of security settings has to be done. The best way to setup Kafka and Schema registry with key store is to launch the kafka_test_setup.sh and ./start_schema_registry.sh. The script has the job to create keystore for schema registry, export it certificate and install on a truststore used by the client pipeline. All this security artifacts are available under the./tls_repository directory in plugin's clone.

1. clone the repo and launch:

   ./kafka_test_setup.sh
   ./start_schema_registry.sh

2. install a schema in the registry, for example

   curl --location --request POST 'http://localhost:8081/subjects/logstash_test-value/versions' \
   --header 'Content-Type: application/vnd.schemaregistry.v1+json' \
   --data-raw '{"schema": "{\"namespace\": \"io.confluent.examples.clients.basicavro\", \"type\": \"record\", \"name\": \"Payment\", \"fields\": [     {\"name\": \"id\", \"type\": \"string\"},     {\"name\": \"amount\", \"type\": \"double\"} ]}"}'

   • if you want to use the HTTPS, add to the curl

     --cacert /path/to/logstash-integration-kafka/tls/schema_reg_certificate.pem   

   • point to port 8083 and switch protocol tohttps
3. in a local Logstash configure the Gemfile to point to the plugin:
   • adds in Gemfile

     gem "logstash-integration-kafka", :path => "/path/to/logstash-integration-kafka"

   • install it

     bin/logstash-plugin install --no-verify

4. execute a pipeline with leverages the schema registry trust store setting:

   
   input {
   kafka {
   bootstrap_servers => ["localhost:9092"]
   topics => ["logstash_test"]
   group_id => "logstash"
   consumer_threads => 2
   schema_registry_url => "https://localhost:8083/"
   schema_registry_ssl_truststore_location => "/path/to/logstash-integration-kafka/tls/clienttruststore.jks"
   schema_registry_ssl_truststore_password => "changeit"
   key_deserializer_class => "org.apache.kafka.common.serialization.ByteArrayDeserializer"
   }
   }

output { stdout { codec => rubydebug } }

5. verify no errors happen in log

## Related issues

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- Closes #123
- Relates #123
- Requires #123
- Superseeds #123
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- Closes #101 
- Relates https://github.com/confluentinc/schema-registry/pull/957

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