filtering for spk find/search

[dcookspi]

spk ls has simple filtering based on the current host's host options settings. We discussed having richer filtering with a --filter-by option, or similar, e.g.

• --filter-by opt=value must have name and value match
• --filter-by opt?=value matches if does not have name, but if has name must have value
• allow multiple filters with and, or and various operators
• allow configuration for the default filtering

See meeting notes from 2024-03-134 meeting for more details.

Originally posted by @dcookspi in #1005 (comment)