fix(core): accept the documented requestManager crawler option

[NotAFlightRisk]

Went to share a queue between two crawlers, found requestManager in the BasicCrawlerOptions docs, and passing it throws before anything runs:

ArgumentError: Did not expect property `requestManager` to exist, got `[object Object]` in object `BasicCrawlerOptions`

The key just isn't in optionsShape, and ow.object.exactShape is the first thing the constructor does - so the handling below it, including the "cannot be used in conjunction with requestList and/or requestQueue" error, is unreachable. No way round it short of subclassing.

Borrowed the validator key list from the one on v4 so the two branches agree. Every subclass spreads optionsShape, so this covers Cheerio/ Playwright/ Puppeteer/ JSDOM/ HTTP too.

Happy to drop the validators entry and use a plain ow.optional.object if you'd rather keep the diff to one line.