Adds pg17 files to postgres_exporter

[tony-landreth]

Description

This PR adds pg17 files to help transition off of postgres_exporter.

Please indicate what kind of change your PR includes (multiple selections are acceptable):

• Other

Testing

None of the testing listed below is optional.

• Installation method:
  • Binary install from source, version:
  • OS package repository, distro, and version:
  • Local package server, version:
  • Custom-built package, version:
  • Other:
• PostgreSQL, Specify version(s): 17

Code testing

Have you tested your changes against:

• RedHat/CentOS

If your code touches postgres_exporter, have you:

• Tested against all versions of PostgreSQL affected
• Ensure that exporter runs with no scrape errors

[hunleyd]

needs a changelog fragment, otherwise lgtm