Add checklists to contributing guidelines

[florianm]

Feature

Changing one seemingly harmless thing can introduce breaking changes to users, tests, hosted docs. The onus of not forgetting any possible breakage could be reduced through providing check lists for:

• Adding a Dependency: DESC, GH actions workflow install steps, binder install.R file, any installation instructions
• Renaming a vignette: ODK Central "analyze.vue" modal, links from README
• Probably low prio to add now, but would have loved to have checklists on adding functions similar to X (e.g. handle_ru_* helpers required a very similar but also complex chain of changes)
• Adding or updating test forms
• Updating package data

Revdeps:

• ODK Central frontend, docs
• urODK
• R pkgs wastdr, turtleviewer, etlTurtleNesting