More explicit error message for invalid scenario

[buixor]

When a scenario fails to be loaded (ie. because the filter is incorrect), the error message could make the incriminated scenario more obvious.

Currenty:

time="29-05-2020 13:19:54" level=error msg="Failed to load bucket : invalid filter 'evt.Meta.log_type in ['http_access-log', 'http_error-log'] && any(File('sqli_probe_patterns.txt'), {Upper(evt.Parsed.http_args) contains Upper(#)})' in /etc/crowdsec/config/scenarios/http-sqli-probing.yaml : unknown func Upper (1:101)\n | evt.Meta.log_type in ['http_access-log', 'http_error-log'] && any(File('sqli_probe_patterns.txt'), {Upper(evt.Parsed.http_args) contains Upper(#)})\n | ....................................................................................................^"
time="29-05-2020 13:19:54" level=fatal msg="Scenario loading failed : loadBucket failed : invalid filter 'evt.Meta.log_type in ['http_access-log', 'http_error-log'] && any(File('sqli_probe_patterns.txt'), {Upper(evt.Parsed.http_args) contains Upper(#)})' in /etc/crowdsec/config/scenarios/http-sqli-probing.yaml : unknown func Upper (1:101)\n | evt.Meta.log_type in ['http_access-log', 'http_error-log'] && any(File('sqli_probe_patterns.txt'), {Upper(evt.Parsed.http_args) contains Upper(#)})\n | ....................................................................................................^"

Mentioning directly that "the scenario crowdsecurity/http-sqli-probing failed to be load because ..." would make user's life easier !