Replace the nullpointer checking in the Planning Scene with std::optional

[AndyZe]

Please ping @henningkayser or @tylerjw before starting this issue! It's just an idea.

Stuff like this:

std::unique_ptr<ObjectTypeMap> object_types_;

  if (!object_types_)
  {
    ObjectTypeMap kc;
    parent_->getKnownObjectTypes(kc);
    object_types_ = ObjectTypeMap(kc);
  }
  else
  {
    ...

Ought to be replaced with std::optional<ObjectTypeMap>.

#2132 is a good start at this that seems like it could be extended for:

scene_transforms_, robot_state_, acm_, object_types_

[SuyashSapkal]

Hi @AndyZe , @tylerjw and @henningkayser

I would like to work on this. Let me know what things I should be working on.

[AndyZe]

I think we need to at least wait for a review of #2132 first. If it's acceptable, you could apply the same techniques again.

Thanks @SuyashSapkal

[MEHARRAJ]

I would like to work on this. Let me know what things I should be working on.

[sjahr]

@MEHARRAJ Thank you, feel free to open a PR with the necessary changes

[zearocode]

Hi @AndyZe @tylerjw , I would like to work on this issue . May I know what changes should I do ?

[utkarshanand140]

Hey @AndyZe @tylerjw , has there been any progress on this ? If not, I would like to start work on this. Kindly lemme know.