Implement Btrieve ACS

[paladine]

• Implements Btrieve ACS functionality + adds relevant tests
• Adds a version number to the Btrieve database for schema compatibility
• Speeds up unit tests by using a shared in memory account db for unit tests (not just integration)
• Handles database Stream reads to make sure we read the entire Stream

[paladine]

• Also added a Seek cursor direction for KeyEqual queries, instead of using that hack >= query + manual key validation. Manual key validation would have been more difficult given ACS. Makes sense to just let sqlite do it

[enusbaum]

formatting changes