Emit adding/removing interfaces for object serverHEADmaster

The object server currently either creats the objects and interfaces, or
defer the signal by not adding objects.

In practice, we have situations that the code would like to add
interfaces to an existing object, and it's not supported, or needs
tricky code to workaround.
Exmaples:
https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-bmc-code-mgmt/+/5820
https://gerrit.openbmc-project.xyz/c/openbmc/openpower-pnor-code-mgmt/+/5346

This commit adds the support by:
1. Adding emit_added() in interface.hpp and the generated server.hpp
2. Adding a enum class in object's constructor to indicate which action
   to do, to create the object, or adding the interface, or defer signal
   as before.

So the user of object<> could pass `action::emit_interface_added` to the
constructor to tell the object server *only* emit interface added to
DBus, without emitting object added.
The previous code stays the same behavior:
* If `true` is passed in object's constructor, it defers emitting object
  added signal;
* If no extra parameter is passed in object's constructor, it emits
  object added signal as before.

Tested: 1. Make sure the openbmc builds fine with
        https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-logging/+/25089
        because phosphor-logging uses its own server.hpp for interface, the
        above patch removes that.
        2. Manually write a small service to verify the interfaces are
        added and removed by using the `emit_interface_added` action.
        3. Added the unit test cases for object.hpp to check the
        ctor/dtor with different actions.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I178c5bed3c9ff39ee2ac8d143fbe9131b0753dfa

0 files changed, 0 insertions, 0 deletions