Use `resmush.it` to optimize static assets

[AlexAxthelm]

Closes #336

Optimize static image assets using resmush.it (via R package {resmush})

Visual inspection reveals no noticeable differences in checked files, but I leave this to maintainers to determine if this is a change you want to make.

R4.4.0> list.dirs("inst/extdata/", full.names = TRUE) |> stringr::str_subset(pattern = "img$") |> resmush::resmush_dir(overwrite
              = TRUE)
ℹ Resmushing 118 files
🕔  Go! | ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■  100% [1m 0.6s] | ETA:  0s (118/118 files)
══ resmush summary ════════════════════════════════════════════════════════════════════════════════════════════════════════════════════
ℹ Input: 118 files with size 16.8 Mb
✔ Success for 118 files: Size now is 7.6 Mb (was 16.8 Mb). Saved 9.3 Mb (55.01%).
See results in directories inst/extdata//PA2022CH_de_exec_summary/img, inst/extdata//PA2022CH_en_exec_summary/img,
inst/extdata//PA2022CH_fr_exec_summary/img, inst/extdata//PA2022FL_en_exec_summary/img, inst/extdata//PA2024CH_de_exec_summary/img,
inst/extdata//PA2024CH_en_exec_summary/img, and inst/extdata//PA2024CH_fr_exec_summary/img.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 9.69%. Comparing base (91a070f) to head (9607d3c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #337 +/- ## ===================================== Coverage 9.69% 9.69% ===================================== Files 27 27 Lines 2187 2187 ===================================== Hits 212 212 Misses 1975 1975 ```

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[AlexAxthelm]

@MonikaFu @jacobvjk putting this into review. You can preview rendered reports/summaries at https://github.com/RMI-PACTA/workflow.transition.monitor/pull/327#issuecomment-2175763933

[MonikaFu]

See my comment in https://github.com/RMI-PACTA/pacta.executive.summary/issues/336#issuecomment-2178935144