NetServices: format code using `haiku-format`

This commit formats all the netservices2 code with the `haiku-format` tool from
https://github.com/owenca/haiku-format (commit aa7408e), with the following
customizations:
* SpaceBeforeRangeBasedForLoopColon is set to false
* Braces before a catch block are not wrapped
* Most headers, except for ExclusiveBorrow.h, have been manually reformatted
to adhere to Haiku's header format (issue #19 in the repository)

Change-Id: I693c4515cf26402e48f35d1213ab6d5fcf14bd1e

NetServices: implement hostname resolution and connection for BHttpRequest

BHttpSession::Execute() moves the request into the session, and returns a future BHttpResponse
object. Currently implemented are resolving the hostname, and opening the connection.

There is some scaffolding for the actual data transfer.

Change-Id: I5a8a7a7f8680036b91cdba4beee140bbed6bfd5a

NetServices: move token validation to header for reuse elsewhere

Change-Id: I2dbed5cfbd387eaf6ed7cf38c73a7db865a87771