Fix compilation errors for ros2 client on Foxy

[eliasdc]

Bug fix

Fixed bug

Fixes #110, #111

Fix applied

Reverted back to default parameters when declaring each parameter to support Foxy builds. This results in a slight behavior change where you're now able to run the node without setting any parameters.

Added an additional fix where it was comparing or calculating with two timestamps with different clock types resulting in a crash. The solution correctly sets the ROS_TIME clock type when adding the location to the robot path.

[eliasdc]

Foxy build works but I haven't tested it at runtime. On Galactic I ran an entire setup including rmf, adapters, free fleet and custom robots.

[aaronchongth]

Thanks for making the changes! The build works fine for me too, however I am having some trouble running the turtlebot3 simulation example. Trying to figure out what changed with nav2 between Foxy and Galactic, other than the rmw

[eliasdc]

@aaronchongth quite a lot has changed in nav2 Galactic. I remember having lots of configuration conflicts/mistakes, e.g. some recovery services changed names.

[aaronchongth]

@eliasdc Thanks for confirming. Since that remaining part is just for launching an example, it be a better idea to have this merged and comment in documentation that the example works for Galactic only