Add to the ImHashMap ref state arguments to be propagated into the Update delegates

[dadhi]

Pros:

• The idea is that we pass the struct state deep into the stack when updating (other ops) on Map
• We may get the result back using this stack, like the old value, some calculated value, etc.
• Encourage the passing state, by enabling more scenarios where you can pass it, and avoid memory allocation and performance hit introducing closure in delegate.
• Have the fewer overloads because passing the struct parameter by ref enables to combine multiple state items into one without hurting performance.