Added EncapsulatedOptions::merge() and accompanying test

[Bilge]

This PR implements option merging for EncapsulatedOptions such that two compatible instances may be merged into each other. This is a common use case since a provider may supply options and a resource supplies its own superset of the same options class which need to be combined before they're forwarded to the connector.

There are some interesting questions raised by this.

1. Should the merged options become a new instance or modify one of the existing instances?
2. Should merging consider only the options or copy in the default values as well?
   1. If it should consider defaults, should it do so for one or both instances?
3. What should be the default merge strategy? Is a simple union sufficient or should it be recursive?
4. How should merging be implemented in a derived class? Simple method override or strategy pattern?

Currently this PR implements the following answers to these questions, subject to change.

1. Existing instance is mutated.
2. Only options are considered, default values are ignored.
3. Simple array union of options.
4. Simple method override.

[Bilge]

TODO: This value type checking needs to be extended to recursively check array values and defaults.

[Bilge]

This is no longer needed since #48, which removes the need to pass options around, to have multiple option instances, and therefore the need to merge instances together. No longer do we have to make guesses about how different sets of options should be merged because we only ever deal with one set of options and specific option implementations can decide how their properties should be managed, which is an altogether more robust approach.