blockfilter: Functions to translate filter types to/from names.

Summary: This is a partial backport of Core PR14121 : https://github.com/bitcoin/bitcoin/pull/14121/commits/ba6ff9a6f70139594362b4b4a6b816707bb165c8

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D6335