Update font awesome icon labels for FA 6

[cicdguy]

Update font awesome icon labels for FA 6, to avoid warnings like:

This Font Awesome icon ('some icon') does not exist:
* if providing a custom `html_dependency` these `name` checks can 
  be deactivated with `verify_fa = FALSE`

[github-actions]

Code Coverage Summary

Filename                         Stmts    Miss  Cover    Missing
-----------------------------  -------  ------  -------  -------------------------------------------
R/default_filter.R                   7       7  0.00%    17-27
R/dummy_functions.R                 74      61  17.57%   12-95
R/example_module.R                  17      17  0.00%    19-35
R/get_rcode_utils.R                 52       2  96.15%   94, 99
R/get_rcode.R                      131      50  61.83%   66, 73, 78, 139-148, 212-261
R/include_css_js.R                  20       0  100.00%
R/init.R                            39      21  46.15%   171, 182-183, 236-257
R/log_app_usage.R                   38      38  0.00%    34-119
R/logging.R                         13      13  0.00%    11-28
R/module_nested_tabs.R             113      16  85.84%   57, 96, 100-117, 163, 212, 257
R/module_tabs_with_filters.R        66       0  100.00%
R/module_teal_with_splash.R         33       2  93.94%   62, 74
R/module_teal.R                    119      20  83.19%   49, 52, 142-143, 156-162, 168-174, 197, 227
R/modules_debugging.R               19      19  0.00%    41-60
R/modules.R                        115       9  92.17%   218, 423-448
R/reporter_previewer_module.R       12       2  83.33%   18, 22
R/show_rcode_modal.R                20      20  0.00%    17-38
R/utils.R                            6       0  100.00%
R/validations.R                     62      39  37.10%   103-355
R/zzz.R                             11       7  36.36%   3-14
TOTAL                              967     343  64.53%

Results for commit: 7312685

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[github-actions]

Unit Tests Summary

    1 files    10 suites   11s ⏱️
107 tests 107 ✔️ 0 💤 0 ❌
207 runs  207 ✔️ 0 💤 0 ❌

Results for commit 9f444f9.

[Polkas]

maciejnasinski@Maciejs-MacBook-Air NESThub % grep -rn --include \*.R -e "icon(" ./teal        
./teal/R/module_teal.R:85:      icon("sync", "spin fa-spin"),
./teal/R/include_css_js.R:84:    shinyjs::hidden(icon("cog")), # add hidden icon to load font-awesome css for icons
./teal/R/module_tabs_with_filters.R:118:      tags$span(icon("fas fa-bars"))