fix(esm-shim): use mlly to find index to append shim

[younggglcy]

Rollup Plugin Name: {@rollup/plugin-esm-shim}

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

If yes, then include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

This PR should resolve #1842

Description

1. provide named esm export
2. keep track with https://github.com/unjs/unbuild/blob/main/src/builders/rollup/plugins/cjs.ts, so findStaticImports is used to find index to append code shim, which is implemented with AST. The original ESMStaticImportRegex is dropped.

[tada5hi]

LGTM

Thanks :)