refactor: remove parsing of case directory paths for case metadata

[gknapp1]

Currently, some applications parse the list of expected Myna output files in the input file to determine which cases to run.

For example:

Myna/src/myna/application/adamantine/temperature_part_pvd/app.py

Lines 51 to 66 in 04c35ab

	def parse_mynafile_path_to_dict(self, mynafile):
	"""Parses the path of the output Myna file into a dictionary containing the
	build, part, and layer names as strings and the case_dir and mynafile as Path
	objects.
	The path to the Myna file is expected to be in the format:
	`working_dir/build/part/layer/stepname/mynafile`
	"""
	dir_parts = Path(mynafile).parent.parts
	case_dict = {
	"build": dir_parts[-4],
	"part": dir_parts[-3],
	"layer": dir_parts[-2],
	"stepname": dir_parts[-1],
	"case_dir": Path(mynafile).parent,
	"mynafile": Path(mynafile),
	}

Instead of each application handling this separately, a centralized method for loading the case specifications (parts, layers, regions, etc.) should be defined in the Myna core functionality to have self-consistent behavior, avoid needing to validate paths from settings file, and reduce code duplication.