Add way to pass HTML form to FormData creation

[aronerben]

According to https://developer.mozilla.org/en-US/docs/Web/API/FormData/FormData, the constructor should be able to take an optional <form>/HTMLFormElement.

[aronerben]

As it is, this introduces a cirular dependency between Browser.Dom and Browser.Blob (therefore this is a draft), how should this be resolved? Should I extract FormData into its own file?

[MangelMaxime]

I suppose the only clean way to resolve would be to merge Browser.Blob and Browser.Dom together.

But if we go this way I wonder, if you should not merge back all the packages together. This would be easier for the consumer too because if he wants to target the Browser he would only have 1 package to import.

I think the original split was to make designing the API/Packages easier and also perhaps a faster compilation. I think faster compilation is false good idea in this case.

@alfonsogarciacaro What do you think?