shell: Register dialogs separately from pages

So that the upcoming refactoring can be done without having to bother
with dialogs.  Dialogs will get their own makeover.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Make cockpit.loc private

And refer to it as "page navigation parameters".

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Explicitly pass default host to embedded components

We will keep doing this when the current 'machine' option goes away.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: New-style URLs

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Separate page parameters into host, path, and options

Also remove the old { page: "..." } construct from the API and strip
the prefix from the path when passing it to embedded components.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Test hash encoding/decoding

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Move shell-specific semantics out of cockpit.hash

Reviewed-by: Stef Walter <stefw@redhat.com>
common: Allow telling pipe not to touch stderr

This should be used in test-server, so that people debugging can
see cockpit-bridge output on the real terminal stderr.
bridge: Ignore possibly fatal warnings when installing polkit agent

This is a workaround for a polkit bug, which emits a pretty strong
g_warning() when it can't install a polkit agent. We ignore this
warning, but also ignore the possibly fatal debugging abort()
here.
common: Include new lines in stderr output when forwarding

When forwarding stderr output to the logs, include new lines so
that the when the messages are also relayed to stderr they look
correct.
common: Simpler removing of signal handlers in CockpitPipeTransport
ws: Use 'cat' as a mock bridge in certain tests

This is simpler, faster, and makes a lot less journal and valgrind
noise.