Add action send_goal prototype completer

[artivis]

Add an action goal prototype completer to ros2 action send_goal.
E.g.

$ ros2 action send_goal /fibonacci action_tutorials/action/Fibonacci [tab][tab]
-f          --feedback  order:\ 0\ 

Not very pretty but one can at least figure out the first few characters of the goal body.
Then,

$ ros2 action send_goal /fibonacci action_tutorials/action/Fibonacci "o [tab]

resolves to,

$ ros2 action send_goal /fibonacci action_tutorials/action/Fibonacci "order: 0"

This follows the work initiated in #298.

Signed-off-by: artivis [email protected]

[ivanpauno]

LGTM. I left a minimal comment.

[artivis]

@ivanpauno I'll wait on your feedback and final approval of this PR before updating #299 & #300.

[ivanpauno]

LGTM, thanks for the contribution!
I manually tested it, and it works well.

Sanity check:

• Linux:

[ivanpauno]

• Linux:

@artivis There's a linter failure, could you address it? Thanks!

[artivis]

@artivis There's a linter failure, could you address it? Thanks!

Sure thing !

[artivis]

@ivanpauno Should be fixed now.
I didn't realized that I had a broken version of flake8-docstrings .

[ivanpauno]

@ivanpauno Should be fixed now.
I didn't realized that I had a broken version of flake8-docstrings .

I tested locally, and linter is passing (and auto-completion continues working well).
I'm merging this, thanks for the PR @artivis.

[ivanpauno]

@artivis another minimal comment: try to avoid force pushing if it's not completely necessary, it does the review process harder.