feat(VolumeViewport): Add getImageIds to volume viewport

[jlopes90]

Context

This adds the getImageIds method to the VolumeViewport.

Changes & Results

Added getImageIds to the VolumeViewport class, now you can get image ids for the volume viewport.

Testing

https://deploy-preview-758--cornerstone-3d-docs.netlify.app/live-examples/volumebasic

cornerstone.getRenderingEngines()[0].getViewports()[0].getImageIds();

Checklist

PR

• My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• My code has been well-documented (function documentation, inline comments,
  etc.)

• I have run the yarn build:update-api to update the API documentation, and have
  committed the changes to this PR. (Read more here https://www.cornerstonejs.org/docs/contribute/update-api)

Public Documentation Updates

• The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• "OS: Windows 10
• "Node version: 18.12.0
• "Browser: Chrome Version 116.0.5845.111 (Official Build) (64-bit)

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[sedghi]

Thanks for your contribution. see my comments

[sedghi]

Looks great. This is a great contribution, thanks a lot!