Feature/sc 455513/allow using key pair credentials in raster

[josemaria-vilaplana]

Proposed Changes

Snowflake key pair authentication support. See: Key-pair authentication

2 new options added to snowflake commands:
--private-key-path: Path to your privake key in PEM format
--private-key-passphrase: Passphrase for private key if it's encrypted (optional)

Example:

carto snowflake upload \
  --file_url https://... \
  --database my-snowflake-database \
  --schema my-snowflake-schema \
  --table my-snowflake-table \
  --account my-snowflake-account \
  --warehouse my-warehouse \
  --username my-snowflake-user \
  --private-key-path /path/to/my/privatekey.pem \
  --private-key-passphrase my-passphrase \
  --band 1 \
  --cleanup-on-failure \
  --overwrite

Pull Request Checklist

• I have tested the changes locally