adds a state machine implementation for `ordered_elements` constraint

[desaikd]

Issue #56:

Description of changes:

This PR works on adding an NFA state machine for validating ordered_elements constraint.

List of changes:

• adds implementation of a state machine to use for validation of ordered_elements
• adds changes for using nfa for validation
  • builds nfa using NfaBuilder and uses NfaRun to validates ordered_elements constraint
  • adds a function to retrieve non negative range boundaries in Range
  • modifies to correctly check for overlapping types in ordered_elements constraint (non greedy)

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[desaikd]

As per an offline discussion, moving all the information to Transition instead of State resolves the weirdness around entry/exit condition checks on states instead having those checks to see if we can take a given transition or not.

List of change:

• adds changes to store all information in Transition instead of states.
• removes State as all states are now intermediate states which removes complexity invoved with types of states
• moves all entry/exit methods for State to Transition
• states are now simply usize which its represents states id
• NFA build process now creates a set of states that are final states or accepted states of NFA

QQ: Should we still keep the Initial and Final state? or at least an initial state? (I have added a transition to itself for the initial state in order to start the validation process from initial state. Another option would be to perform an initial transition for state_id = 0 and visits = 0 explicitly).

QQ: Should we add a transition that skips optional states while building NFA? (If we have an initial state then we can remove the recursive calls for optional states to get all possible transitions. And simply add a transition that skips all optional states in the build process) - reference discussion https://github.com/amazon-ion/ion-schema-rust/pull/149#discussion_r1119360000