[ZEPPELIN-6338] Allow separate frontend modules to use different Node/NPM versions

### What is this PR for?
Moved the `node.version` and `npm.version` properties from the parent `pom.xml` to each module's `pom.xml`.
This allows `zeppelin-web` and `zeppelin-web-angular` to manage their Node/NPM versions independently.

Note: Each module installs and manages its own Node/NPM, so this change simply makes that independence explicit without adding extra maintenance burden or increasing package size.

### What type of PR is it?
Improvement


### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-6338

### How should this be tested?
Check CIs if Node and npm is installed for both modules.

### Questions:
* Does the license files need to update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? No


Closes #5084 from tbonelee/update-nodejs.

Signed-off-by: ChanHo Lee <chanholee@apache.org>