feat: proper range request handling

[ari-party]

This pull request is a follow up on #576.

Changes:

• Datasource get() support for byte ranges (local datasource tested, s3 follows docs, supabase unsure as not in docs, please test supabase!)
• Datasource size() now returns null if a file wasn't found or there was an error (0 byte files are still files)
• Proper range request handling and responses (above change is now used to see if a file exists or not)

Minor changes:

• Change @types/node version to 18
• Fix Dockerfile casing warnings

Please reply if you have questions or comments!