Fix app entry point adjustments in Echo installation

[joetannenbaum]

This PR addresses several small bugs:

• The import regex wasn't matching multi-line imports and imports that didn't end with a semi colon
• Fixed a bug where we weren't injecting the Echo code into non-TS files
• In order for the ->toOthers() to work, we now add the websocket ID to all Inertia requests as follows:

router.on('before', (event) => {
    const id = echo().socketId();

    if (id) {
        event.detail.visit.headers['X-Socket-ID'] = id;
    }
});

Fixes laravel/echo#447