Reimplement ArchiveBase using ArrayStore

[btjanaka]

Description

This PR refactors the ArchiveBase to place data in ArrayStore rather than in separate NumPy arrays. This should make the archive more flexible and easier to extend in the future.

While flexibility is the end goal, note that this PR is only a refactor; thus, no API changes are being made. As a result, tests will mostly remain the same.

The exception is the creation of a private ribs.archives._transforms module, for which we do introduce new tests. This module should be considered unstable for now, but once it seems more stable, we can make it public.

TODO

• Modify ArchiveBase
• Update SlidingBoundariesArchive
• Create private transforms module
• Test transforms
• Fix ArchiveBase tests where appropriate

Questions

Status

• I have read the guidelines in
  CONTRIBUTING.md
• I have formatted my code using yapf
• I have tested my code by running pytest
• I have linted my code with pylint
• I have added a one-line description of my change to the changelog in
  HISTORY.md
• This PR is ready to go