Add sqlcommenter fields

[jonadaly]

Description

Add new fields for SQLCommenter:

• "application", which should contain the name of the application
• "action", which should contain the HTTP verb in the request

Both are documented in the spec for SQLCommenter, and (for example) both are accepted by Google Cloud when displaying Query Insights.

Note that "app_name" is already included, but "application" is the field expected in the spec.

Open questions:

• Should I remove the original app_name field? I can't see this one described in the spec.
• Should I copy these changes over to the other implementations for SQLCommenter in this library (dbapi, flask, psycopg2, sqlalchemy)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tested by:

• using this modified copy of the library in a production app
• updated unit tests

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: jonadaly / name: Jon Daly (313f044, 88c13c2, e725dd9, 6e4188e, 52acf87)

[jonadaly]

@shalevr could you take a look at this please? There's no owner for the django component in .github/component_owners.yml, so I've pinged you as SQLAlchemy is Django-ORM-adjacent 😆