Update generator - reducing the number of installation steps

[enowmbi]

This PR updates the generator to streamline the installation process by reducing the number of manual steps required.
The goal is to improve the developer experience by making setup easier and more intuitive.

Changes Include:

1. Added a few methods in the generator to include previously manual setup steps(install and run generators, add entry in routes.rb file).
2. Updated documentation to reflect the simplified installation flow.

Benefits:

1. Quicker onboarding for new users.
2. Fewer opportunities for setup errors.
3. Cleaner and more maintainable code in the generator.

Testing:

1. Verified generator runs successfully with default and custom options.
2. Confirmed that all generated apps function as expected post-installation.

[a-chacon]

Thank you! Please review the only comment I leave.

[a-chacon]

hey @enowmbi there are some tests failing. Take a look at it please! About the lint, don't worry, I can update dependencies on other PR.

[enowmbi]

sure, I'll take a look.

[a-chacon]

hey @enowmbi still failing:

# Running:

The file /home/runner/work/rails-url-shortener/rails-url-shortener/test/dummy/tmp/generators/config/routes.rb does not appear to exist
...............................F

Failure:
RailsUrlShortener::RailsUrlShortenerGeneratorTest#test_generator_runs_without_errors [test/lib/generators/rails_url_shortener/rails_url_shortener_generator_test.rb:14]:
Expected file "config/initializers/rails_url_shortener.rb" to exist, but does not

bin/rails test test/lib/generators/rails_url_shortener/rails_url_shortener_generator_test.rb:10



Finished in 0.251549s, 127.2118 runs/s, 349.8324 assertions/s.
32 runs, 88 assertions, 1 failures, 0 errors, 0 skips

Sorry but I am working and I dont have time to check what is causing the problem.

[enowmbi]

ok, let me know if you find something.

[enowmbi]

@a-chacon, I think I fixed the broken tests. Looking forward to your approval and merging.

[a-chacon]

@enowmbi thanks!