Fix copilot-setup-steps: replace reusable workflow with direct steps

[m7pr]

This PR fixes the GitHub Copilot setup workflow by replacing the reusable workflow call with direct steps, as required by GitHub Copilot's limitations for copilot-setup-steps jobs.

Changes:

• Removed uses: insightsengineering/r.pkg.template/.github/workflows/copilot-setup-steps.yaml@main
• Added direct steps for checkout, R setup, and dependency installation
• Uses actions with uses: (which is allowed) instead of reusable workflows (which are not)

This resolves the error: 'Calling a reusable workflow with the uses: keyword is not supported in copilot-setup-steps jobs.'

[github-actions]

Unit Tests Summary

  1 files   16 suites   1m 55s ⏱️
170 tests 170 ✅ 0 💤 0 ❌
391 runs  391 ✅ 0 💤 0 ❌

Results for commit eebb9ff.

♻️ This comment has been updated with latest results.

[github-actions]

Unit Test Performance Difference

Test Suite	$Status$	Time on main	$±Time$	$±Tests$	$±Skipped$	$±Failures$	$±Errors$
plot_with_settings_ui	💚	$53.40$	$-1.17$	$0$	$0$	$0$	$0$

Results for commit 3852475

♻️ This comment has been updated with latest results.

[github-actions]

Code Coverage Summary

Filename                      Stmts    Miss  Cover    Missing
--------------------------  -------  ------  -------  ------------------------------------------------------
R/basic_table_args.R             23       0  100.00%
R/draggable_buckets.R            87      12  86.21%   116-121, 151-156
R/get_dt_rows.R                  13       0  100.00%
R/ggplot2_args.R                 49       0  100.00%
R/nested_closeable_modal.R       20      20  0.00%    83-103
R/optionalInput.R               255      79  69.02%   190, 315-389, 402-409, 411-416, 434, 436, 501, 583-596
R/panel_group.R                  39      39  0.00%    50-136
R/plot_with_settings.R          309      16  94.82%   299-305, 327, 364, 373-374, 390, 578-579, 581, 583
R/standard_layout.R              52       4  92.31%   90-93
R/table_with_settings.R         158       1  99.37%   100
R/utils.R                         7       0  100.00%
R/verbatim_popup.R              105      35  66.67%   113-114, 116, 124-155
R/white_small_well.R              7       0  100.00%
TOTAL                          1124     206  81.67%

Diff against main

Filename      Stmts    Miss  Cover
----------  -------  ------  --------
TOTAL             0       0  +100.00%

Results for commit: eebb9ff

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results