Make the CivetOutput viewer more tolerant of missing files

[prioux]

I regularly see exception raised internally in CBRAIN when people are trying to view incomplete CIVET outputs.

We should make the view code more tolerant, it should show what it can and inform the user about what is missing.

I'm attaching the stack trace of one such event. It shows the view code was trying to open the 'verify' subdirectory.

Errno::ENOENT: No such file or directory @ dir_initialize - 35580-1-2022-06-08/verify

BrainPortal/app/models/data_provider.rb:615:in `open'
BrainPortal/app/models/data_provider.rb:615:in `entries'
BrainPortal/app/models/data_provider.rb:615:in `block in cache_collection_index'
BrainPortal/app/models/data_provider.rb:608:in `chdir'
BrainPortal/app/models/data_provider.rb:608:in `cache_collection_index'
BrainPortal/lib/smart_data_provider_interface.rb:155:in `cache_collection_index'
BrainPortal/app/models/userfile.rb:596:in `cache_collection_index'
BrainPortal/app/models/userfile.rb:188:in `list_files'
BrainPortal/cbrain_plugins/installed-plugins/userfiles/civet_output/views/_civet_output.html.erb:33:in `_cbrain_plugins_installed_plugins_userfiles_civet_output_views__civet_output_html_erb__2404919374744253284_60485600'