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.