Update project plugins's properties

Update project plugins's properties

This patch updates various properties of the project's plugins. Those
properties are publicly visible through the API or with the CLI's `help`
command.

The updated properties are:

Descriptions:
    Updated to add details or normalize them.

Authors:
    All changed to `EfficiOS <https://www.efficios.com/>`. Keeping a
    specific up-to-date list of authors will be challenging in the
    future, especially with many contributors.

Help texts:
    Added to refer to specific manual pages.

    Maybe we can find a way to set a manual page's plain text as a
    component class's help text in the future, but in the meantime at
    least the user knows where to look for help.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I44d13a89039e433c06e1c527eb2be577fd471454
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2047
CI-Build: Simon Marchi <simon.marchi@efficios.com>
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>