* updated parameter names in function signatures
* addressed return type of "CSS functions"
* simplified StylesConfig and SelectComponentsConfig
* updated type of base parameter in styleFn
* removed invalid property from HTML select element
* moved existing "react-select" definitions into "v1" directory
* updated references to V1 of "react-select"
* dts-gen --dt --name react-select --template module
* added placeholders for react-select definitions and tests
* fixed imports of react and react-select
* updated config. files
* drafted definitions for react-select
* updated definitions for react-select
* made Props in stateManager.d.ts and Select.d.ts optional
* handle grouped options in Select.d.ts
* updated definitions for react-select
* resolved merge conflicts
* fixed issues identified by "npm test"
* updated type of "menuPortalTarget"
* remove OptionType type and introduce throughout as a generic parameter
* add an extra type
* re-enable interface-over-type-literal lint rule
* parameterize GroupedOptionsType
after some consideration this should be parameterized, typically with a union type, see Grouped example which is a select of `ColourOption | FlavourOption`
