fix($compile): use the correct namespace for transcluded svg elements

[tbosch]

Via transclusion, svg elements can occur outside an <svg> container in an
Angular template but are put into an <svg> container through compilation
and linking.

E.g.
Given that svg-container is a transcluding directive with
the followingg template:

<svg ng-transclude></svg>

The following markup creates a <circle> inside of an <svg> element
during runtime:

<svg-container>
  <circle></circle>
</svg-container>

However, this produces non working <circle> elements, as svg elements
needs to be created inside of an <svg> element.

This change detects for most cases the correct namespace of transcluded content
and recreates that content in the correct <svg> container
when needed during compilation. For special cases it adds an addition argument
to $transclude that allows to specify the future parent node of elements
that will be cloned and attached using the cloneAttachFn.

Related to #8494

[caitp]

Maybe templateNamespace is a better name for this, but it's weird --- A) because these values are not actually namespaces, and B) because it's a breaking change for not much of a real reason given A).

If we're going to call it namespace, the values should probably be proper XML namespaces, but we don't do this because people are going to have a much easier time remembering "svg" than "http://www.w3.org/2000/svg"

IMO we should change the symbol name within $compile --- so that the compiler is easier to understand, but the public api doesn't have an unneeded change

[tbosch]

Your are right, but I chatted with Igor to leave it.

[tbosch]

Don't have a better name than "namespace"... (type is really too general)

[jbedard]

If futureParentNode is changed to be a node (like its name implies) instead of a jQuery object then .parent() can change to [0].parentNode to avoid the extra jQuery object...