Reduce excessive whitespace in large Javadoc hover documentation

[amritamishra01]

Summary

This PR reduces excessive whitespace in large Javadoc hover and completion documentation.

Long Javadoc content such as java.util.regex.Pattern preserved repeated spaces, tabs, and excessive blank lines, which inflated the rendered markdown size and caused large hover popups to waste vertical space.

Changes

• collapse repeated spaces/tabs into a single space
• collapse 3+ consecutive newlines into standard markdown paragraph spacing
• trim leading/trailing whitespace
• preserve existing jdt:// link rewriting behavior

Validation

Tested with java.util.regex.Pattern hover, especially the Quotation, Boundary matchers, and Special constructs sections that previously showed large whitespace gaps.

The hover now renders more compactly and allows significantly more regex constructs to be visible in the same viewport.

fixes# #4219