Support dynamic (star-based) index names

- Changes `.index_name=` accessor to declarative `.index_name`, which
  mutates when arguments are passed: an index name and options.

- Options includes `:wildcard`, a proc that accepts a record (or nil)
  and is used to substitute a '*' in an index name. It can be accessed
  later via the `.wildcard` class reader.

- Queries against unexpanded wildcards, inserts against the substitution.

Signed-off-by: Stephen Celis <stephen@stephencelis.com>