Fix the TypeScript type for the backgroundColor prop

[hmu332233]

Hello,
I read the issue(#428) and would like to suggest a solution to this

Chalk's backgroundColor type is declared as follows.
https://github.com/chalk/chalk/blob/main/index.d.ts#L31-L49

export type BackgroundColor =
	| 'bgBlack'
	| 'bgRed'
	| 'bgGreen'
	| 'bgYellow'
	| 'bgBlue'
	| 'bgMagenta'
	| 'bgCyan'
	| 'bgWhite'
	| 'bgGray'
	| 'bgGrey'
	| 'bgBlackBright'
	| 'bgRedBright'
	| 'bgGreenBright'
	| 'bgYellowBright'
	| 'bgBlueBright'
	| 'bgMagentaBright'
	| 'bgCyanBright'
	| 'bgWhiteBright';

However, in ink, there is a code to attach bg prefix (https://github.com/vadimdemedes/ink/blob/master/src/colorize.ts#L8-L14),
so there is no need to attach bg.
Therefore, I suggest to use chalk's ForegroundColor type as auto-complete.

[vadimdemedes]

Thank you!