Avoid to mutate user options

[Aschen]

What does this PR do?

Before this PR we were mutating user options passed to SDK method (eg: document:search).
It could lead to confusion because the user may want to reuse the same options object across different calls.

How should this be manually tested?

$ kourou collection:create index collection

This code should print { from: 0, size: 42 } two times.

const { Kuzzle, WebSocket } = require('./index')

const kuzzle = new Kuzzle(new WebSocket('localhost'));

(async () => {
  await kuzzle.connect();

  const options = { from: 0, size: 42 }
  console.log(options)
  await kuzzle.document.search('index', 'collection', {}, options)
  console.log(options)

  kuzzle.disconnect();
})();

Other changes

• remove custom errors when the result of server:now or server:adminExists is unexpected

[codecov]

Codecov Report

Merging #511 into 7-dev will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            7-dev     #511      +/-   ##
==========================================
- Coverage   95.81%   95.75%   -0.07%     
==========================================
  Files          32       32              
  Lines        1315     1295      -20     
==========================================
- Hits         1260     1240      -20     
  Misses         55       55              

Impacted Files	Coverage Δ
src/controllers/Collection.js	100.00% <ø> (ø)
src/controllers/Security.js	97.05% <ø> (-0.07%)	⬇️
src/controllers/Document.js	94.91% <100.00%> (-0.33%)	⬇️
src/controllers/Server.js	100.00% <100.00%> (ø)

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