Drop support for React 16

[ggdouglas]

Drop support for React 16/17 and update peerDependencies across packages.

In package.json:

blueprint/packages/core/package.json

Lines 63 to 67 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/datetime/package.json

Lines 52 to 56 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17",
	"react": "^16.8 || 17",
	"react-dom": "^16.8 || 17"
	},

blueprint/packages/datetime2/package.json

Lines 49 to 53 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/docs-theme/package.json

Lines 46 to 50 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/icons/package.json

Lines 49 to 53 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/select/package.json

Lines 48 to 52 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/table/package.json

Lines 48 to 52 in ca86eeb

	"peerDependencies": {
	"@types/react": "^16.14.41 || 17 || 18",
	"react": "^16.8 || 17 || 18",
	"react-dom": "^16.8 || 17 || 18"
	},

blueprint/packages/test-commons/package.json

Lines 25 to 28 in ca86eeb

	"peerDependencies": {
	"react": ">=16.8",
	"react-dom": ">=16.8"
	},

Also these references:

blueprint/packages/core/src/components/icon/icon.tsx

Lines 104 to 109 in ca86eeb

	/**
	* ReturnType here preserves type compatability with React 16 while we migrate to React 18.
	* see: https://github.com/palantir/blueprint/pull/7142/files#r1915691062
	*/
	// TODO(React 18): Replace return type with `React.ReactNode` once we drop support for React 16.
	<T extends Element = Element>(props: IconProps<T>): ReturnType<React.FC<IconProps<Element>>> | null;

blueprint/packages/icons/src/svgIconContainer.tsx

Lines 45 to 50 in ca86eeb

	/**
	* ReturnType here preserves type compatability with React 16 while we migrate to React 18.
	* see: https://github.com/palantir/blueprint/pull/7142/files#r1915691062
	*/
	// TODO(React 18): Replace return type with `React.ReactNode` once we drop support for React 16.
	<T extends Element = Element>(

blueprint/packages/datetime2/src/components/dateFnsLocalizedComponent.tsx

Lines 44 to 46 in ca86eeb

	// HACKHACK: type fix for setState which does not accept partial state objects in our version of
	// @types/react (v16.14.x)
	public setState<K extends keyof S>(