Update rosdep help and logging for ROS 2.

[cdhabecker]

[Problem]

• Git staging is cluttered with build files in install/ and log/.
• Argument <stacks-and-packages> (which relies on stack.xml and manifest.xml) does not make sense for ROS 2.
• Help text for --ignore-src is unclear whether it ignores the input pkgs or the dependency pkgs or both.
• The --verbose output does not show all the packages that rosdep thinks are installed (or available in the workspace).
• The --verbose output prints some lines out of order.
• The --verbose output prints dupes of keys, e.g., "resolve_all: rsource [pkg3] requires rosdep keys [pkg1 pkg1 pkg1]", followed by 3 identical lines describing the action.

[Solution]

• Modified .gitignore. Verified that the repo does not currently have any files in install/ or log/.
• Modified command usage. Split the check, install, and key commands into variants "ROS 1 or 2" and "ROS 1".
• Modified help text for --ignore-src. Added "--ignore-src:" marker to verbose log lines.
• Added verbose logging for --ignore-src that displays the packages that rosdep finds at AMENT_PREFIX_PATH_ENV_VAR. (The first part of --ignore-src, where it finds ROS_PACKAGE_PATH packages, already has verbose logging via find_catkin_packages_in().)
• Updated verbose logging in find_catkin_packages_in() so that it is on stdout and, therefore, prints in order with the other stdout lines.
• Updated resolve_all() to make the list of rosdep_keys unique.

[Test]

• Manual, local test on jammy-amd64. See https://gist.github.com/cdhabecker/250790b665240d2be8a24b1afe01eaae.

[cdhabecker]

See test output at https://gist.github.com/cdhabecker/250790b665240d2be8a24b1afe01eaae.