Add host_role config option and store more data in metadata

Added

• Add the host_role config option. This config option can be set per host to generate some metrics automatically per host and possibly do things like grouping in the future.

Changed

• Bump agent to 6bec691.
  • Upgrade sql_lexer to v0.9.5. It adds sanitization support for the THEN and ELSE logical operators.
• Bump agent to version d789895.
  • Increase short data truncation from 2000 to 10000 characters.

See the changelogs for AppSignal for Elixir package 2.7.8 for more information.