chore: merge lexer into tokenizer file (#83)

Lexer wasn't part of public API: vite config and package.json didn't
mention it, only tokenizer.

Author: bartveneman

src/index.ts

@@ -14,7 +14,7 @@ export { type ParserOptions } from './parse'
 
 // Types
 export { CSSNode, type CSSNodeType, TYPE_NAMES, type CloneOptions, type PlainCSSNode } from './css-node'
-export type { LexerPosition } from './lexer'
+export type { LexerPosition } from './tokenize'
 
 export {
 	ATTR_OPERATOR_NONE,