Pass all Ky options to hooks

[sholladay]

Closes #167
Closes #182
Closes #187

This PR:

• Updates the options object passed to hooks so that all Ky and fetch options are included. For context: in Ky v0.15.0 and earlier, a subset of Ky options were included in the options object (e.g. prefixUrl was included, but throwHttpErrors was not, without any clear justification).
• Loosens the validation of certain options so that hooks can pass their options (which are already normalized) to Ky to make a new request using the same options. For example, the json option now takes precedence over body, rather than being mutually exclusive with body. Additionally, searchParams can now be any value supported by URLSearchParams(), which makes it possible to use a boolean as a param value, provide the params as an array of entries, etc.
• Removes our reliance on the document object, which was previously used in some circumstances to determine the base URL of the page, from which we resolve relative URLs. The Request class is now used to achieve the same goal. Request is significantly easier to polyfill and is much more likely to be available in web workers and non-browser environments.
• Drops support for Sets throughout the API for simplicity. This should not have any meaningful performance impacts, since the lists of HTTP methods and status codes are inherently small in size, even if you were to include all valid methods and status codes. See Pass all Ky options to hooks #188 (comment).

[sindresorhus]

@sholladay Thanks for doing this much needed improvement and cleanup. 🙌 Do you plan any other changes or should I go ahead and release this?

[sholladay]

@sindresorhus should be good to release. 👍

I will be working on #193 late tonight/tomorrow. Do you think we should consider that a breaking change (it would error previously)? If so, maybe we'd want to include it in this release. But I'm fine with letting it slip to the next one.

[sindresorhus]

Almost anything is a breaking change for someone. I can wait to publish a new release. No rush.