sink.ctf.fs: append error causes where relevant

sink.ctf.fs: append error causes where relevant

The `sink.ctf.fs` component class doesn't append error causes when it
encounters errors.  This makes the error reporting very vague.  For
example, both when the user fails to pass the required `path` parameter
and when they pass a path to a directory they don't have write
permissions on, they get:

    ERROR:    [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2462)
      Cannot create components.
    CAUSED BY [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2277)
      Cannot create component: plugin-name="ctf", comp-cls-name="fs", comp-cls-type=4, comp-name="sink.ctf.fs"
    CAUSED BY [libbabeltrace2] (/home/simark/src/babeltrace/src/lib/graph/graph.c:1055)
      Component initialization method failed: status=ERROR, comp-addr=0x60c000011d40, comp-name="sink.ctf.fs", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="fs",
      comp-class-partial-descr="Write CTF traces to the file sys", comp-class-is-frozen=1, comp-class-so-handle-addr=0x607000000100,
      comp-class-so-handle-path="/home/simark/build/babeltrace/src/plugins/ctf/babeltrace-plugin-ctf.la", comp-input-port-count=0, comp-output-port-count=0

Add calls to append error causes where relevant.  It becomes much easier
to distinguish the errors:

    ERROR:    [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2462)
      Cannot create components.
    CAUSED BY [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2277)
      Cannot create component: plugin-name="ctf", comp-cls-name="fs", comp-cls-type=4, comp-name="sink.ctf.fs"
    CAUSED BY [libbabeltrace2] (/home/simark/src/babeltrace/src/lib/graph/graph.c:1055)
      Component initialization method failed: status=ERROR, comp-addr=0x60c000011d40, comp-name="sink.ctf.fs", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="fs",
      comp-class-partial-descr="Write CTF traces to the file sys", comp-class-is-frozen=1, comp-class-so-handle-addr=0x607000000100,
      comp-class-so-handle-path="/home/simark/build/babeltrace/src/plugins/ctf/babeltrace-plugin-ctf.la", comp-input-port-count=0, comp-output-port-count=0
    CAUSED BY [sink.ctf.fs: 'sink.ctf.fs'] (/home/simark/src/babeltrace/src/plugins/ctf/fs-sink/fs-sink.c:74)
      Error validating parameters: missing mandatory entry `path`

and

    ERROR:    [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2462)
      Cannot create components.
    CAUSED BY [Babeltrace CLI] (/home/simark/src/babeltrace/src/cli/babeltrace2.c:2277)
      Cannot create component: plugin-name="ctf", comp-cls-name="fs", comp-cls-type=4, comp-name="sink.ctf.fs"
    CAUSED BY [libbabeltrace2] (/home/simark/src/babeltrace/src/lib/graph/graph.c:1055)
      Component initialization method failed: status=ERROR, comp-addr=0x60c000011e00, comp-name="sink.ctf.fs", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="fs",
      comp-class-partial-descr="Write CTF traces to the file sys", comp-class-is-frozen=1, comp-class-so-handle-addr=0x607000000100,
      comp-class-so-handle-path="/home/simark/build/babeltrace/src/plugins/ctf/babeltrace-plugin-ctf.la", comp-input-port-count=0, comp-output-port-count=0
    CAUSED BY [sink.ctf.fs: 'sink.ctf.fs'] (/home/simark/src/babeltrace/src/plugins/ctf/fs-sink/fs-sink.c:40)
      Cannot create directories for output directory: Permission denied: output-dir-path="/tmp/pouet/yo"

Change-Id: I384e88a1d2629ac75495518c8bce2a2cba2f9741
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/3907
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>