Enhance search experience for Aliki

[ccmywish]

Recently, I have been extensively using the current https://docs.ruby-lang.org/en/master/, I like aliki so much, but I find I want it more convenient to use. So I add/adjust these features:

1. Use Escape to leave search region
2. Use / to search globally
3. Use s to search instance methods in the current module page
4. Use Shift + s to search class methods in the current module page
5. Autocomplete single : to ::

[ccmywish]

@st0012

This is not a big change. Could you please take a look and review it?

[matzbot]

🚀 Preview deployment available at: https://68231662.rdoc-6cd.pages.dev (commit: 0205a6e)

[ccmywish]

The preview page does't work with s and Shift + s because the page lacks .html suffix (Maybe cloudflare page service hides it?), so the match failed:

UPDATE: I submitted an additional commit to make it compatible with this.