Fix using "propTypes" instead of "PropTypes" for checking types

[maxceem]

Reported by Vigneshkumar:

• We're using "Component.PropTypes" (with uppercase P) instead of Component.propTypes (lowercase p) in around 16 places in the whole codebase. I guess the typo was introduced in one component and has been copy-pasted multiple times.

• Using PropTypes doesn't actually detect the problems. For example, skillsCategory can be undefined in TalentPickerQuestion component. But it's marked as required. We're supposed to get an error in such a scenario according to prop types. But We'll not see the error message as we're using PropTypes.

• We have such issues in Connect App and in react-components repositories

[maxceem]

Sum up:

• we have to fix it in https://github.com/appirio-tech/connect-app/ and https://github.com/appirio-tech/react-components/tree/feature/connectv2 repositories.
• make sure that no warnings are produced in browser console after the fixes
• don't remove any propTypes if the props are not actually removed
• adjust types if necessary