Code cleanup in com.sun.tools.jdi

There is some opportunity to clean up coding in package com.sun.tools.jdi.

In detail:
- Clean up import blocks: Remove unneeded statements, expand unqualified package imports, sort them
- Correct formatting and line spacing issues
- Remove some redundant super interface declarations
- Remove unnecessary casts
- Remove obsolete coding

This issue is similar to JDK-8181417 which took care of classes in packages com.sun.jdi.*