Suggestions for improving REVM API

[Wodann]

• Receive reference to changes in DatabaseCommit::commit
• Receive reference to all parameters in DatabaseRef
• Remove DatabaseRef and always use &self for immutable methods in the trait
  • People can use internal mutability for caching
  • Simplifies codebase
• Rename DatabaseCommit to DatabaseMut to signal that it requires &mut self, similar to functions like get_mut