move pptx and xlsx and csv and R files to own directories

[njr2128]

related to #129, just as we have created and moved all .docx files into a /static/docx/ directory and .pdf files into /static/pdf/, do the same for the .pptx and .xlsx files:

./activity-sheets/activitysheet_mordants-dyes-recipes-automatic-calculator.xlsx
./activity-sheets/rosenkranz_2019_dyes_TEMPLATE-AND-RECIPES_dye-experiments.xlsx
./activity-sheets/su22_fld_cunningham_annika_onion-skin-dyeing-template+notes-2-greens.xlsx
./activity-sheets/su22_fld_cunningham_annika_onion-skin-dyeing-template+notes.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_pl.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_pro.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_said.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_say.xlsx
./student-projects/fa21_jacobson_beah_final-project-know_tl_know.xlsx
./student-projects/sp23_gorup-sophie_final-project_image-sources.xlsx
./student-projects/sp23_gorup_sophie_final-project_quantitative-analysis-of-margaret-baker-and-ms-fr-640.xlsx
./student-projects/su21_branscum_final-project_recipe-data.xlsx
/mnt/c/Users/naomi/Github/research-teaching-companion/static/documents (issue129a) $ find . -name '*.pptx'
./activity-sheets/2023_dyes-pigments_samples.pptx
./student-projects/sp19_kaplan_final-project-indexing-ingredients-presentation.pptx
./student-projects/sp23_brown_reece_final-project_dye-workshop-presentation.pptx
./student-projects/sp23_gorup_sophie_final-project_women-at-work.pptx
./student-projects/su21_snyder_mellon_final-project-pigments.pptx

[njr2128]

Also for R and CSV:

./activity-sheets/2023_dyes-pigments_samples.pptx
./activity-sheets/activitysheet_mordants-dyes-recipes-automatic-calculator.xlsx
./activity-sheets/rosenkranz_2019_dyes_TEMPLATE-AND-RECIPES_dye-experiments.xlsx
./activity-sheets/su22_fld_cunningham_annika_onion-skin-dyeing-template+notes-2-greens.xlsx
./activity-sheets/su22_fld_cunningham_annika_onion-skin-dyeing-template+notes.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_pl.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_pro.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_said.xlsx
./student-projects/fa21_ghoneima_hana_final-project_tl_say.xlsx
./student-projects/fa21_jacobson_beah_final-project-know_tl_know.xlsx
./student-projects/sp19_kaplan_final-project-indexing-ingredients-presentation.pptx
./student-projects/sp23_brown_reece_final-project_dye-workshop-presentation.pptx
./student-projects/sp23_gorup-sophie_final-project_image-sources.xlsx
./student-projects/sp23_gorup_sophie_final-project_quantitative-analysis-of-margaret-baker-and-ms-fr-640.xlsx
./student-projects/sp23_gorup_sophie_final-project_women-at-work.pptx
./student-projects/su21_branscum_final-project_recipe-data.xlsx
./student-projects/su21_branscum_ingredients_fr-640.csv
./student-projects/su21_branscum_ingredients_granville.csv
./student-projects/su21_branscum_ingredients_hall.csv
./student-projects/su21_branscum_ingredients_pudsey.csv
./student-projects/su21_branscum_ingredients_totals+percents.csv
./student-projects/su21_branscum_recipe-types_fr-640.csv
./student-projects/su21_branscum_recipe-types_granville.csv
./student-projects/su21_branscum_recipe-types_totals+percents.csv
./student-projects/su21_macomber_figures.R
./student-projects/su21_snyder_mellon_final-project-pigments.pptx