blockfilter: Refactor and add tests for BlockFilter construction

Summary:
This is a backport of core PR 14172
e4ed8ce2c blockfilter: Remove default clause in switch statement.
c30620983 blockfilter: Additional constructors for BlockFilter.
20b812993 blockfilter: Refactor GCS params into struct.

Depends on D2867

Test Plan: make check

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Maniphest Tasks: T589

Differential Revision: https://reviews.bitcoinabc.org/D2872