feat: remove option for legacy hson files

[AngRodrigues]

• Prevents the use of a config file as json or hjson.
• Included an utils function to convert from old legacy file - update_from_legacy_file
• if the argument config_filename is used, returns ValueError.

Usage example of converter function, using in the hjson file in here:

from map2loop.project import Project
from map2loop.utils import update_from_legacy_file


bounding_box = {
    "minx": 520000,  "miny": 7490000,  "maxx": 550000,  "maxy": 7510000,   "base": -3200,   "top": 1200,
}

loop_project_filename = "local_source.loop3d"

proj = Project( 
    geology_filename = r"source_data\geol_clip_no_gaps.shp", # required
    structure_filename = r"\source_data\structure_clip.shp", #required
    dtm_filename = r"source_data\dtm_rp.tif", # required
    config_dictionary = update_from_legacy_file(filename=r"source_data\example.hjson"),
    working_projection = "EPSG:28350",
    bounding_box = bounding_box,
    loop_project_filename = loop_project_filename,
    overwrite_loopprojectfile = True, 
)

[AngRodrigues]

A note that I will merge this into 3.2 by COB today if no review