[WIP] feat($httpUrlBuilderFactory): introduce new service abstracting url building

[jmendiara]

Here you have my proposal for having configurable strategies for $http url building.
This is a WIP, and tries to solve same problems than #11238 addresses, but with a different perspective, covering more use cases and adding more freedom.

Key points:

• New service $httpUrlBuilderFactory, that serves as foundation for making totally custom urls.
• Default overridable implementation in core
• Users can customize per request how a url is built, or set a new default to the whole app.

Rationale:
URL Building and parameter serialization are complementary problems.
Serialization can be seen as converting objects to a set of {key, value} Strings, and URL Building is aggregating this set to create an encoded URL (?key=value) With this separation, users can rehuse some of the parts: how to serialize (var arr = [1,2] => {arr[], 1}, {arr[],2}) and how to build (encode, concat params with ; ...)

Having in mind keeping core small, and give full control to user for easy customization, only the current building URL is shipped, but the users can make whatever they want. jquery and other param serialization would be coded easily in userland.

Examples

// Example 1: Making pirate URLs
angular.module('App')
.factory('pirateBuildUrl', function($httpUrlBuilderFactory) {
  function pirateSerializer(params, addKeyValue) {
    //params is the $http request `params` config property
    angular.forEach(params, function(value, key) {
      addKeyValue('ARR' + key, value);
    });
  }
  return $httpUrlBuilderFactory(pirateSerializer);
})
.config(function($httpProvider) {
  //Specify default urlBuilder for the whole app 
  //Compatibility with defaults.cache usage: you can set also a function here
  $httpProvider.defaults.buildUrl = 'pirateBuildUrl';
})
.run(function() {
  $http.get('http://myapi.com/things', {
    params: {
      id: 5
    },
    // or specify per request urlBuild (or a function, like the `cache` property)
    buildUrl: 'pirateBuildUrl'
}); // GET http://myapi.com/things?ARRid=5

// Example 2: freedom in urlBuilding. Crazy things are possible. Nice for testing
angular.module('App')
.factory('testBuildUrl', function() {
  return function(url, params) {
    return url + '?' + JSON.stringify(params); 
  };
})
.run(function() {
  $http.get('http://myapi.com/things', {
    params:  { id: 5 },
    buildUrl: 'testBuildUrl'
}); // GET http://myapi.com/things?{"id":5}

I'd this full core customization available in userland, and forget about crazy tests and interceptors to communicate with complex backends. WDYT?

[jmendiara]

Closed by decision taken in #11238