Change all shared_ptr references to shared_ptr

[naiveHobo]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#2966
Primary OS tested on	Ubuntu 20.04
Robotic platform tested on	Gazebo simulation of turtlebot3

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Description of contribution in a few bullet points

• Changed all const shared_ptr & references to shared_ptrs so counter increment takes place properly

Description of documentation updates required from your changes

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[mergify]

@naiveHobo, please properly fill in PR template in the future. @SteveMacenski, use this instead.

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[SteveMacenski]

Just needs https://navigation.ros.org/migration/Galactic.html Migration guide for API change (towards the top)

[SteveMacenski]

Diff with 8 lines
--- src/simple_smoother.cpp
+++ src/simple_smoother.cpp.uncrustify
@@ -27 +27 @@
-  std::string name, std::shared_ptr<tf2_ros::Buffer> /*tf*/,
+  std::string name, std::shared_ptr<tf2_ros::Buffer>/*tf*/,
@@ -29 +29 @@
-  std::shared_ptr<nav2_costmap_2d::FootprintSubscriber> /*footprint_sub*/)
+  std::shared_ptr<nav2_costmap_2d::FootprintSubscriber>/*footprint_sub*/)

[SteveMacenski]

I made the change, just waiting on another run of CI