Add Machine Learning panel group

[qchiujunhao]

Summary

• Move Machine Learning out from under the Statistics and Visualization group in the Main tool panel layout.
• Add a dedicated Machine Learning header with Classical ML and AutoML, Deep Learning, and Multi-omics ML sections.
• Update the All Tools and Imaging panel views to reference the new section IDs.

Companion PR

• usegalaxy-tools install-list companion PR: Split usegalaxy.org Machine Learning tools into focused sections usegalaxy-tools#1512
• This PR provides the UI placement for the new sections introduced there and should be merged together with it.

Validation

• Parsed env/main/files/galaxy/config/tool_conf.xml as XML.
• Parsed env/main/files/galaxy/config/panel_views/all_tools.yml and imaging.yml as YAML.
• git diff --check.