[Improvement] Add validation checks to the startup scripts to prevent incorrect usage

[liuchunhao]

What would you like to be improved?

For users who are new to Gravitino, many attempt to launch Gravitino services using the script located at /gravitino/bin, such as /gravitino/bin/gravitino.sh, which is only a script template.

The correct way is to run ./gradlew clean build -x test compileDistribution, which will compile and generate all artifacts into the directory /gravitino/distribution/package, including /gravitino/distribution/package/bin/gravitino.sh.
Then you can use /gravitino/distribution/package/bin/gravitino.sh to launch the services.

How should we improve?

To avoid the above misuse, we have a few suggestions to prevent mistakes:

1. Add a .template extension to the scripts bin/gravitino.sh, gravitino-iceberg-rest-server.sh, and common.sh to ensure they cannot be run by accident.
2. Add a check for the GRAVITINO_VERSION environment variable in the gravitino.sh.template and gravitino-iceberg-rest-server.sh.template scripts. If GRAVITINO_VERSION is not assigned, print an error message and exit the script.
3. Ensure that only the scripts in the distribution/package/bin/ directory have the GRAVITINO_VERSION environment variable set.

[liuchunhao]

I would like to work on this