Local-friendly RSpec setup

[thejonroberts]

What github issue is this PR for, if any?

No Issue, concerns local development only.

What changed, and why?

Prior to change, running bin/rspec locally would produce following error in my (mac) environment:

lib/ruby/gems/3.2.0/gems/spring-4.2.1/lib/spring/application.rb:105:in `block in preload': Spring reloads, and therefore needs the application to have reloading enabled.
Please, set config.cache_classes to false in config/environments/test.rb.

(Note I did not do what the above error says to do, that was the 'old' way to do it before Rails 7.1, I guess rspec hasn't updated the error?)

So, the only way to run a specific spec or file was to use focus tag (fit, fdescribe, etc...) while running bin/rails spec, which runs javascript/css builds each run - annoying if running backed / not changing javascript/css. The focus tag could also be forgotten about and committed.

This change allows copy/pasting lines from failure notifications, for example, bin/rspec path/to/file.rb:23. Used ENV["CI"] so that CI test run speed is not affected.

Also made a change that filters gems from backtrace of spec failures, which aren't very useful. Typically, I only want to see trace of files we have control over. This can be overridden by passing option to rspec bin/rspec --backtrace. I added a comment to that effect.

[elasticspoon]

LGTM. I don't use bin/rspec but it did not work before this fix and it works now 👍