[ui/public/utils] Copy rarely used items to where they are consumed

[lukeelmers]

Part of #51560

There are a few utils in src/legacy/ui/public/utils that are small and not widely used. Rather than find a "shared" place for them to live, it is probably cleaner to just copy them to the places that rely on them:

• case_conversion
  • keysToSnakeCaseShallow + tests
    • copy to src/legacy/server/status/lib
    • remove duplicate from src/legacy/utils/case_conversion.ts
  • keysToCamelCaseShallow + tests
    • copy to src/legacy/core_plugins/kibana/public/management
    • remove duplicate from src/legacy/utils/case_conversion.ts
• collection tracked in Kibana app migration: Move static code dependencies into kibana_legacy plugin #50670
  • move+ tests 👉 src/legacy/core_plugins/timelion
    • also copy to src/legacy/ui/public/vis/editors/default
  • organizeBy + tests 👉 src/legacy/ui/public/indexed_array
  • pushAll + tests -- delete, unused
• diff_object + tests 👉ui/state_management
• function + tests 👉ui/state_management
  • also copy to ui/directives/watch_multi
• key_map 👉ui/directives
  • also update import from src/test_utils/public
• math
  • leastCommonMultiple 👉ui/vis (update imports in ui/vis/lib and ui/vis/editor
  • greatestCommonDivisor -- move with leastCommonMultiple, but do not export as it is unused outside of this file
• numeric 👉src/legacy/core_plugins/kibana/public/management
• parse_interval 👉src/legacy/core_plugins/data/common
• sort_prefix_first 👉x-pack/legacy/plugins/kuery_autocomplete
• string_utils 👉ui/saved_objects
  • also copy to src/legacy/core_plugins/kibana/public/management
• supports 👉src/legacy/core_plugins/tile_map/public
• Document changes[0] in the ui/public cleanup section of the dev docs issue Dev Docs entry: ui/public & angular cleanup 7.6 #43511

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)

[alexwizp]

@lukeelmers almost all items were resolved in #53819 except

collection
   move+ tests 👉 src/legacy/core_plugins/timelion
   also copy to src/legacy/ui/public/vis/editors/default .  

Not sure if we should create new duplicates of the code. Let's try to find a more suitable place for this file.