fix: Resolve some type problems

[vonagam]

Continues #1566.

Don't know why types started to fail only after my changes, but i found and fixed reason for failures:

In LegacyHookFunction app property on potentially returned context was required to be of the same type as on passed in context. And because of this it was creating variance problems between simple feathers app and express wrapped app, through such forbidden chain:

(expressApp as FeathersApp).service('some').hooks({after: (context) => ({app: feathersApp, ...otherStuff})});

Since we don't care about returned context, simply relaxed type there. In turn such relaxation allowed to improve type of options in hooks method of app itself (and not on service through which the problem was exposed).

Other bonus small changes:

• Updated ExpressUseHandler as you mentioned. I missed that one, but it was not a cause for the failings. Also created separate overload for when path is a regexp.

• Keep ServiceTypes and AppSettings from feathers app during express wrapping.

• In app.use | Application should be inside ternary expression, not outside.

[daffl]

Perfect, thank you! I was actually wondering why it was working before, too when I was looking into it. This looks great.