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 BHttpStatusCode, BHttpStatusClass and Redirects

The user of the API can set whether redirects should be followed, and if so,
how many. This is part of the BHttpRequest API. The BHttpSession then follows
those instructions, and executes the maximum number of redirects the user
would like to follow.

As part of this commit, the BHttpStatusClass and BHttpStatusCodes helper enums
have been added, to give a friendlier access to HTTP status codes and status
classes.

Change-Id: Ic8c9e3fda158e2cce549c8f1d360951f7ac83311

NetServices: implement support for HEAD requests and 204 responses.

These particular responses will not have a body. This is now handled by the
BHttpSession object. There is also a minor fix in here that prevents a crash
when multiple requests are handled by the DataThread at the same time, and not
all of the requests have events.

Change-Id: I7f47d8b3cd8491c8193275be4b3fc1080780fa20

NetServices: partial implementation of the receive function

This initial implementation contains a lot of extra debuggin output that will
be removed in future changes. It is now possible to run a simple GET request
to the test server with gzip encoding.

Change-Id: I2c402e5cf80b94b366563888222a891a1b094b7a

NetServices: Initial implementation of BHttpResult

Incomplete class, but will provide the basis to start working on the internals of the BHttpSession.

Change-Id: I3ca14b7bd823fc1b4a5a32f5784592d214c4e9a7