[java] Throwing warnings for non-W3C before creating session

[diemol]

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Description

This improves checking for non-W3C caps just before the session creation is requested. We were doing that when every capability was being set, which could throw false positives.

Motivation and Context

Removing JWP support in upcoming releases.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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[diemol]

Merging as Java CI passes.