Use constants for VSCode extension views and commands

[dotNomad]

This PR adds readonly constants for the views (like "posit.publisher.homeView") and the commands (like "posit.publisher.configurations.clone").

This makes the code much more searchable using CTRL+F and "Find References". It also makes it much easier to audit, and compare the TypeScript to the package.json file.

Intent

Part of #1766

Type of Change

• • [ ] Bug Fix
• • [ ] New Feature
• • [ ] Breaking Change
• • [ ] Documentation
• • [x] Refactor
• • [ ] Tooling

Approach

This PR doesn't change any functionality, just changes references to strings and uses the constants. It doesn't change commands, solve the issue of some commands not having functions registered, or remove unused commands.

That will all be done in follow-up PRs to avoid mixing this change with that functional enhancement.

Directions for Reviewers

Smoke-test the many commands of the extension.

[dotNomad]

Just tried to run each avaiable command. Didn't cross reference to see if all are parth of this change or not.

command 'posit.publisher.pythonPackages.edit' not found Command 'Posit Publisher: Go to Publishing Log' resulted in an error [UriError]: Scheme is missing: {scheme: "", authority: "", path: "undefined", query: "", fragment: ""} command 'posit.publisher.pythonPackages.scan' not found Command 'Posit Publisher: View Deployment in Connect' resulted in an error Command 'Posit Publisher: View Deployment in Connect' resulted in an error Cannot read properties of undefined (reading 'contentRecord')

Yep this is expected. This PR was the first in the chain and didn't add the missing commands. This is fixed in a follow-up specifically https://github.com/posit-dev/publisher/pull/1808