Rework PID class API

[christophfroehlich]

While fixing the clang errors I realized that lots of implicit casts to computeCommand were used, and the typical usage was to pass something like period.nanoseconds() and convert it internally to seconds. Because introducing an overload with double dt as argument is ambiguous and might silently break user code, I decided to convert the class methods from camelCase to snake_case (the ros2_control standard), remove the uint64_t version but introduce the following new overloads which converts dt to seconds in a consistent way

• double dt
• rcl_duration_value_t dt_ns
• rclcpp::Duration dt
• std::chrono::nanoseconds dt_ns

I converted the method names of PidROS accordingly as well, but left the only rclcpp::Duration version there.

The old methods remain deprecated, this should not break anything in downstream packages.
AFAIK adding non-virtual methods should not be a problem regarding ABI break?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.31474% with 72 lines in your changes missing coverage. Please review.

Project coverage is 72.47%. Comparing base (beb9767) to head (2a336f1).

Files with missing lines	Patch %	Lines
src/pid_ros.cpp	49.00%	51 Missing ⚠️
src/pid.cpp	63.15%	21 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           ros2-master     #246      +/-   ##
===============================================
- Coverage        75.02%   72.47%   -2.55%     
===============================================
  Files               24       24              
  Lines             1133     1239     +106     
  Branches            89       89              
===============================================
+ Hits               850      898      +48     
- Misses             236      294      +58     
  Partials            47       47              

Flag	Coverage Δ
unittests	72.47% <71.31%> (-2.55%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/control_toolbox/pid.hpp	77.77% <ø> (ø)
include/control_toolbox/pid_ros.hpp	100.00% <ø> (ø)
test/pid_ros_parameters_tests.cpp	100.00% <100.00%> (ø)
test/pid_ros_publisher_tests.cpp	95.23% <100.00%> (ø)
test/pid_tests.cpp	100.00% <100.00%> (ø)
src/pid.cpp	78.18% <63.15%> (-15.07%)	⬇️
src/pid_ros.cpp	58.55% <49.00%> (-12.48%)	⬇️

[mergify]

This pull request is in conflict. Could you fix it @christophfroehlich?

[ViktorCVS]

Great work! All variable and function names have been appropriately replaced in every instance where they appear.

[mergify]

This pull request is in conflict. Could you fix it @christophfroehlich?

[saikishor]

LGTM