Bug 35536: Refine verbose handling in some Koha::Plugins calls

Bug 35536: Refine verbose handling in some Koha::Plugins calls

Three routines in Plugins got the verbose parameter on 35507.
We can refine this a bit further.
The idea here is report when you are installing plugins but not
report when just calling plugins (flooding logs).

[1] GetPlugins: Most callers do not expect (or check) results for
    failing plugins. This patch makes GetPlugins only return
    errors when passing the *errors* flag (in 2 cases).
    [a] The misc/devel script prints warnings now using verbose,
        so does not need the errors flag anymore.
    [b] plugins/plugins-home is the only case left. Tiny adjustment
        to keep current behavior. Fixed colspan in template.
        Does not need verbose in favor of 'errors' (passed to
        template).
    [c] For most calls we do not want verbose. New default is 0.

[2] InstallPlugins
    [a] Disabled verbose in plugin-upload. Not really needed.
        Added a FIXME; we need to improve individual install.
    [b] misc/devel: No warnings anymore when calling InstallPlugins
        after GetPlugins.

[3] get_enabled_plugins
    [a] Plugins->call does not need verbose.
    [b] Plugins->feature_enabled does not need it too.

Test plan:

[1] See previous plan. With TestMR data but without patch, run
misc script and go to plugins-home. Do you see load errors on
commandline or form?

[2] Run plugins/plugins-upload (uploading just some file is good
enough); verify that you do not see TestMR lines in logfile.

[3] Run t/db_dependent/Koha/Plugins/Plugins.t for the additional
test on verbose and errors flag.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>