Separate creation & destroy entities streams (backport #185)

[mergify[bot]]

This is an automatic backport of pull request #185 done by Mergify. Cherry-pick of 0575d523ff5c1ef308c73725b782fdbf525c9043 has failed:

On branch mergify/bp/foxy/pr-185
Your branch is up to date with 'origin/foxy'.

You are currently cherry-picking commit 0575d52.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
    modified:   rmw_microxrcedds_c/src/config.h.in
    modified:   rmw_microxrcedds_c/src/rmw_client.c
    modified:   rmw_microxrcedds_c/src/rmw_graph.c
    modified:   rmw_microxrcedds_c/src/rmw_init.c
    modified:   rmw_microxrcedds_c/src/rmw_microros_internal/types.h
    modified:   rmw_microxrcedds_c/src/rmw_microros_internal/utils.h
    modified:   rmw_microxrcedds_c/src/rmw_microxrcedds_topic.c
    modified:   rmw_microxrcedds_c/src/rmw_node.c
    modified:   rmw_microxrcedds_c/src/rmw_publisher.c
    modified:   rmw_microxrcedds_c/src/rmw_service.c
    modified:   rmw_microxrcedds_c/src/rmw_subscription.c
    modified:   rmw_microxrcedds_c/src/utils.c

Unmerged paths:
  (use "git add <file>..." to mark resolution)
    both modified:   README.md
    both modified:   rmw_microxrcedds_c/CMakeLists.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[github-actions[bot]]

Static memory analysis

Default configuration

MTU: 512 B Input buffer size: 2048 B Input history: 4 Output buffer size: 2048 B Output history: 4

Entity	Qty	Size per unit
Context	2	5616 B
Topic	8	56 B
Service	4	168 B
Client	4	168 B
Subscription	4	168 B
Publisher	4	184 B
Node	4	56 B
Static input buffer	8	2136 B

TOTAL: 31524 B