Make ResourceSelector label prop required

[kevinwcyu]

Makes the ResourceSelector's label prop required.

This was split out as a piece of work from https://github.com/grafana/grafana-aws-sdk-react/pull/33/files#r1044841576.

• ResourceSelector usages https://github.com/search?q=org%3Agrafana+ResourceSelector+language%3ATSX&type=code&l=TSX
• ConfigSelector usages https://github.com/search?q=org%3Agrafana+ConfigSelect+language%3ATSX&type=code&l=TSX (ConfigSelector uses ResourceSelector). Note these components are only used by Athena, Redshift, and Timestream. But I ran yarn build on all of the AWS data sources to check that there are no type errors.

[kevinwcyu]

Actually going to close this. The the label prop is passed through to the InlineField component which accepts an optional label so will just leave this as is.