Support case-sensitive keys in SelectKeyPrompt

[bcheung]

Is your feature request related to a problem? Please describe.
Current implementation lowercases option keys and prevents ability to use distinct lowercase and uppercase keys. This makes common CLI patterns impossible (e.g. 'a' = accept, 'A' = accept all).
Side note: the initialValue lookup is also compared against the un-normalized value, which can place the cursor incorrectly. (see code below)

Describe the solution you'd like
Add support for case-sensitive key matching by removing the lowercasing normalization so comparisons are exact (case-sensitive).
If this is too invasive, consider adding an option to opt into this behavior.

Additional context
I believe this is where everything is normalized to lowercase:

clack/packages/core/src/prompts/select-key.ts

Lines 7 to 28 in 372b526

	export default class SelectKeyPrompt<T extends { value: string }> extends Prompt<T['value']> {
	options: T[];
	cursor = 0;
	constructor(opts: SelectKeyOptions<T>) {
	super(opts, false);
	this.options = opts.options;
	const keys = this.options.map(({ value: [initial] }) => initial?.toLowerCase());
	this.cursor = Math.max(keys.indexOf(opts.initialValue), 0);
	this.on('key', (key) => {
	if (!key || !keys.includes(key)) return;
	const value = this.options.find(({ value: [initial] }) => initial?.toLowerCase() === key);
	if (value) {
	this.value = value.value;
	this.state = 'submit';
	this.emit('submit');
	}
	});
	}
	}

[43081j]

to avoid a breaking change, we could have an option such as caseInsensitive which defaults to true

then i agree we should do this 👍