fix: Unable to Build Projects with FFI Plugins in flutter-elinux

[Losses]

Background

Flutter has modified the way it retrieves plugins. The messageChannel plugins and ffi plugins are now retrieved and imported separately. Currently, the internal implementation of flutter-elinux has not been updated to reflect this change, resulting in build failures for plugins that depend on FFI, such as cargokit and rinf.

Solution

This PR references the official Flutter implementation to provide a fix for this issue. The changes ensure that plugins relying on FFI are correctly compiled and processed.

Important Note

I do not have any experience with C/C++, so I am unable to determine if certain modifications are appropriate. Specifically, I am referring to the changes in the following section:

Link to the specific changes

However, the fix for FFI has been locally verified and is confirmed to be correct and effective.

Changes

• Updated the plugin retrieval mechanism to align with the latest Flutter implementation.
• Ensured that plugins relying on FFI are correctly compiled and processed.

Please review the changes and provide feedback, especially on the C/C++ modifications.

Thank you for your attention to this matter.

FIX: #270

[HidenoriMatsubayashi]

Thank you for sending this PR! But could you please check my comment?

[HidenoriMatsubayashi]

LGTM. Thank you very much!