Added java OpenSearch example

[ktSuW]

There is no OpenSearch VPC example in java, but it is available in python. Therefore, os-vpc-provision codebase is used as a reference for this Java OpenSearch VPC AWS CDK repo.

The followings have been modified.

• All the constants are in the ConstantsVariables.java file.
• amazon-linux-extras install nginx1.12 is no longer available in AL23, please see this article, No, AL2023 does not have extras.. To successfully deploy nginx server, dnf install nginx -y is used.
• I have added Useful resources at the end of OpenSearchStack.java. If you want me to remove them or add them in README.md instead, please let me know. Thanks!

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[kaiz-io]

Build is failing. Make sure your example can synth. Could you fix?

Error: Failed to execute goal org.codehaus.mojo:exec-maven-plugin:3.0.0:java (default-cli) on project os-vpc-provision: An exception occured while executing the Java class. Cannot find asset at /home/runner/work/aws-cdk-examples/aws-cdk-examples/java/opensearch/os-vpc-provision/confs/export_opensearch_dashboards_web_logs.ndjson Error: Error: Cannot find asset at /home/runner/work/aws-cdk-examples/aws-cdk-examples/java/opensearch/os-vpc-provision/confs/export_opensearch_dashboards_web_logs.ndjson Error: at new AssetStaging (/tmp/jsii-kernel-FiOHev/node_modules/aws-cdk-lib/core/lib/asset-staging.js:1:1402) Error: at new Asset (/tmp/jsii-kernel-FiOHev/node_modules/aws-cdk-lib/aws-s3-assets/lib/asset.js:1:736) Error: at Kernel._Kernel_create (/tmp/jsii-java-runtime1439759501146481922/lib/program.js:10104:25) Error: at Kernel.create (/tmp/jsii-java-runtime1439759501146481922/lib/program.js:9775:93) Error: at KernelHost.processRequest (/tmp/jsii-java-runtime1439759501146481922/lib/program.js:11691:36) Error: at KernelHost.run (/tmp/jsii-java-runtime1439759501146481922/lib/program.js:11651:22) Error: at Immediate._onImmediate (/tmp/jsii-java-runtime1439759501146481922/lib/program.js:11652:46) Error: at process.processImmediate (node:internal/timers:476:21) Error: -> [Help 1] Error:
Error: To see the full stack trace of the errors, re-run Maven with the -e switch. Error: Re-run Maven using the -X switch to enable full debug logging. Error:
Error: For more information about the errors and possible solutions, please read the following articles: Error: [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

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