[FEATURE] Allow json5 file extensions for integration configs

[Swiddis]

Is your feature request related to a problem?
#1732 got started on introducing JSON5 support by adding its parsing to the config parsing, so the JSON5 support is live. But currently integrations relies on the file extension being json to find a config, which causes issues with syntax highlighters.

What solution would you like?
Add logic to try both json and json5 extensions when reading config files. Possibly with some sort of regex match?

What alternatives have you considered?
N/A

Do you have any additional context?
#1680