Fix inertia routes helper

[skryukov]

This PR improves inertia routes helper by adding support for:

• namespaced and scoped routes

namespace :settings do
  inertia 'appearance' => 'settings/appearance'
end

scope :settings do
  inertia 'appearance' => 'settings/appearance'
end

• symbol notation for route paths

inertia settings: 'settings'

• shorthand syntax with default component:

inertia :settings # => pages/settings.jsx

namespace :settings do
  inertia :appearance # => pages/settings/appearance.jsx
end

[BrandonShar]

Looks great, thank you! Just a quick question to make sure I understand the code.

[BrandonShar]

Now matter how much Ruby I write, I'm still regularly surprised by syntax 😄

[BrandonShar]

Can you explain what this is doing?

[skryukov]

This overrides defaults coming from the namespace helper. Btw, I missed the resource helper, will update the PR to support it as well.