feat: add a defineConfig utility function and use it in examples

[haoqunjiang]

This commit also exports the createConfig as a named export for consistency in import styles.
I feel that though the name is descriptive enough, it's not a suitable name to be used directly in the defineConfig arguments, so I used import aliases in all examples.

typescript-eslint 8.15 added support for infinitely deep array nesting in the config helper, so I removed all the spread patterns in the examples. typescript-eslint/typescript-eslint#10333

As discussed in vuejs/create-eslint-config#37

/cc @segevfiner

[haoqunjiang]

Gonna need it in my @vue/eslint-config-standard-with-typescript refactor so I'm merging it.

[haoqunjiang]

I think the API is far from ideal - and would like to change it later. Hope I can finish it before New Year, otherwise the ugly API would need to stay for a bit longer.

Current:

import pluginVue from 'eslint-plugin-vue'
import {
  defineConfig,
  createConfig as vueTsEslintConfig,
} from '@vue/eslint-config-typescript'

export default defineConfig(
  pluginVue.configs['flat/essential'],
  vueTsEslintConfig({ extends: 'recommendedTypeChecked', 'stylisticTypeChecked' }),
)

I'm thinking about:

import pluginVue from 'eslint-plugin-vue'
import { defineConfig, configs } from '@vue/eslint-config-typescript'
import standardTypeChecked from '@vue/eslint-config-standard-with-typescript/type-checked'

export default defineConfig(
  pluginVue.configs['flat/essential'],
  configs.recommendedTypeChecked,
  configs.stylisticTypeChecked,
  standardTypeChecked,
)

It'll make defineConfig implementation much more complicated, and may encounter a few edge cases, but the result is much more readable.