ui: workspace file filtering

[tiborsimko]

Current behaviour

Some workflows can produce many files, e.g. reana-demo-cms-h4l:

$ reana-client ls -w h4l | wc -l
840

The CLI allows filtering only files I am interested in:

$ reana-client ls -w h4l --filter name=results
NAME                                           SIZE    LAST-MODIFIED
results/Higgs4L1file.root                      59770   2021-12-07T01:08:44
results/DoubleMuParked2012C_10000_Higgs.root   54181   2021-12-07T01:08:54
results/scramdone.txt                          0       2021-12-07T01:05:44
results/mass4l_combine_userlvl3.pdf            18141   2021-12-07T01:11:04

The web UI currently does not, and offers 56 paginated pages:

Therefore it may take a lot of time to locate desired file in the web UI if one does not use CLI in thiese kinds of situations.

Expected behaviour

It'll be useful to offer a text box where a user could type part of the file name and the web interface would output only those files that match the input pattern. Similarly to how list of workflows can be filtered:

Obviously, with an adapted UX design to fit the Workspace page style.