[Expressions] TypeScriptify and Jestify

[streamich]

• Convert to TypeScript
  • src/legacy/core_plugins/interpreter/server/lib/create_handlers.js
  • src/legacy/core_plugins/interpreter/server/lib/__tests__/create_handlers.js
  • src/legacy/core_plugins/interpreter/server/routes/index.js
  • src/legacy/core_plugins/interpreter/server/routes/server_functions.js
  • src/legacy/core_plugins/interpreter/public/interpreter.test.js
  • src/legacy/core_plugins/interpreter/public/renderers/visualization.js
  • src/legacy/core_plugins/interpreter/public/lib/render_functions_registry.js
  • src/legacy/core_plugins/interpreter/public/lib/render_function.js
  • src/legacy/core_plugins/interpreter/public/functions/visualization.js
  • src/legacy/core_plugins/interpreter/public/functions/index.js
  • src/legacy/core_plugins/interpreter/public/functions/kibana.js
  • src/legacy/core_plugins/interpreter/public/functions/vis_dimension.js
  • src/legacy/core_plugins/interpreter/public/functions/kibana_context.js
  • src/legacy/core_plugins/interpreter/public/functions/__tests__/font.js
  • src/legacy/core_plugins/interpreter/public/functions/kibana.test.js
  • src/legacy/core_plugins/interpreter/public/functions/clog.js
  • src/legacy/core_plugins/interpreter/public/interpreter.js
  • src/legacy/core_plugins/interpreter/test_helpers.js
• Convert tests to Jest
  • src/legacy/core_plugins/interpreter/public/functions/__tests__/font.js
• Replace all instances of any and unknown types by correct TypeScript type
  • src/plugins/expressions
  • src/legacy/core_plugins/expressions
  • src/legacy/core_plugins/interpreter/public/

Parent issue: #44153

[elasticmachine]

Pinging @elastic/kibana-app-arch

[lukeelmers]

@alexwizp Do you think you could take a look at moving this forward as @streamich will be unavailable for several weeks?

I added a note on the WIP PR about using the ExpressionFunction generic, which I know you are already quite familiar with 😄

Ideally we'd work to get that one merged and then move on to the other items included in the list above.