fix: allow to pass options for custom server

[snitin315]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

Yes

Motivation / Use-Case

We already allow server: "own-server-package", so update schema to allow server: { type: "own-server-package" }

Breaking Changes

None

Additional Info

No

[alexander-akait]

Will be great if we will try to integrate fastily and pure http module there, just in tests and if it will be ok, provide examples, because we should move out from express

[codecov]

Codecov Report

Merging #4110 (4049387) into master (69202d9) will not change coverage.
The diff coverage is n/a.

@@ Coverage Diff @@ ## master #4110 +/- ## ======================================= Coverage 92.77% 92.77% ======================================= Files 14 14 Lines 1481 1481 Branches 547 547 ======================================= Hits 1374 1374 Misses 99 99 Partials 8 8 

Impacted Files	Coverage Δ
bin/cli-flags.js	100.00% <ø> (ø)

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[snitin315]

Will be great if we will try to integrate fastily and pure http module there, just in tests and if it will be ok, provide examples, because we should move out from express

Yes, putting it in my TODO.