Run SQLite import WP-CLI command with default PHP version

[fluiddot]

Related to #558.

Proposed Changes

• Allow passing the PHP version to be used when running a WP-CLI command.
• Use default PHP version (8.1) when running sqlite import WP-CLI command. Using a PHP 8 version is required due to SQLite plugin (used in the WP-CLI command) using functions only supported in PHP 8+.

Testing Instructions

• Run the app with the command npm start.
• Create a site.
• Change the PHP version of the site to 7.4.
• Navigate to the Import/Export tab.
• Import a full Jetpack backup file.
• Observe the import process succeeded.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wojtekn]

The code change looks clear.

I reproduced the issue using Studio 1.1.2 and confirmed that this PR fixes that - I was able to import Jetpack Backup to a site that uses PHP7.