net/http: let HTTP_SERVER, HTTP_CLIENT and HTTP_PARSER select HTTP

Due to commit 8308b9bd ("net/http: Add the HTTP/1.1 API")
every user of CONFIG_HTTP_PARSER would need to add CONFIG_HTTP to
their .conf files.  Which is fine for intree samples/tests as they
have been adjusted, but the rest of world working on Zephyr apps
will need to make this changes as well.

Instead, we should have each of the following select HTTP instead of
depend on it, which will make future use of these configs and their
dependencies more intuitive:
HTTP_SERVER
HTTP_CLIENT
HTTP_PARSER

NOTE: As cleanup, this commit also removes the CONFIG_HTTP added to
samples and test .conf files.

Change-Id: I81cfaa19e37333b1bf98778f8147814780e7f77c
Signed-off-by: Michael Scott <michael.scott@linaro.org>