* add some capabilities to the config parser and a stream parser
* style: pre-commit.ci fixes
* add additional tests for the config parser
* additional tests of config sections and indexing
* style: pre-commit.ci fixes
* add initialization for member variables
* warning and error fixes
* add test for `parse_from_stream`
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>