More succint GenesisPaths initialization

[neysofu]

Description

New method GenesisPaths::from_dir which simplifies struct initialization.

Testing

Existing test suite, no new tests.

[codecov]

Codecov Report

Merging #1012 (760acbc) into nightly (9e65601) will decrease coverage by 0.1%.
Report is 4 commits behind head on nightly.
The diff coverage is n/a.

❗ Current head 760acbc differs from pull request most recent head 8414378. Consider uploading reports for the commit 8414378 to get more accurate results

see 3 files with indirect coverage changes

[neysofu]

There's a compilation error related to experimental feature gating; will fix asap.