Need to specify encoding for json load

[HajimeShimizu]

CORE version: 0.10.0

When adding custom standards, following error message is pop up.

"UnicodeDecodeError: 'cp932' codec can't decode byte 0xef in position 0: illegal multibyte sequence"

On windows, json.load method try to apply 'cp932' encoding as a default. In general, JSON files are created by UTF-8 (without BOM) and need to fix. One idea is to add encoding option.

f = open('test.json', 'r', encoding='utf-8')

In this case, following will be target.
cdisc_rules_engine/services/cache/cache_populator_service.py
def add_custom_standard_to_cache(self)

In a meantime, solution is to save JSON file in Shift-JIS encoding.

[SFJohnson24]

this would likely be an extension of #1022 and quite easy at that once the encoding argument can be given via the CLI. We would need to extend that argument to custom standards and also change the default to utf-8 for custom standards