Refactor: Centralise escaping and unescaping urls / URI.escape obsolete warning on Ruby 2.7+

[syphax-bouazzouni]

Issues

• URI.escape is obsolete on Ruby 2.7+
• In some places, we use URI.escape, and on other CGI.escape
• in application helpers, we have two methods that do the same escape(string) and encode_param(string)

Changes

This PR, fix those issues, by centralizing the escaping in only one function called escape(url) that uses CGI.escape. Then reuse it everywhere (same for unescaping).

[jvendetti]

Thank you very much for this pull request and suggested refactor to resolve URI.escape obsoletion warnings. We discussed internally and chose to go with a different fix. Some of the warnings were resolved through usage of Rails path helpers (287788e), and others were resolved by removing defunct marginal notes views (7149982). Removal of the marginal notes views also allowed for deletion of the escape, encode_param, and to_param methods. We didn't see the need to continue wrapping CGI.escape in an escape method since it's still part of Ruby's standard library, and feels like an unnecessary level of indirection.

[syphax-bouazzouni]

Hi, OK great.