Add libuv support as a replacement of systemd + some CMake fixes

[Thor-x86]

This PR solves:

• https://github.com/sony/flutter-embedded-linux/issues/419
• https://github.com/sony/flutter-embedded-linux/issues/402

For further commit description regarding libuv support, see https://github.com/sony/flutter-embedded-linux/commit/7928671070f6b0cd2cda380e8818535bfc7871f1.

[HidenoriMatsubayashi]

Thank you for sending this PR.

I would like to confirm one thing regarding this PR. It's unclear whether we can contribute this software to flutter/engine, but do you agree to delegate all rights related to this PR to Sony?

[Thor-x86]

do you agree to delegate all rights related to this PR to Sony?

Yeah sure! As long as it keep open sourced :)

[HidenoriMatsubayashi]

Thank you.

Please check the CI failure.

[Thor-x86]

Please check the CI failure.

I am not sure if you will like this, but I fixed all styling errors that will disturb the CI. This is a huge change by the way.

[Thor-x86]

Sorry, the commit https://github.com/sony/flutter-embedded-linux/commit/13b92066241cd70db97b415557c1551acaf2c30b was removed because I forgot to exclude the src/third_party/*. Wonder why you didn't use git submodule for the source code dependencies.

[Thor-x86]

I discovered a quirk on clang-format: its output won't be consistent between clang-format versions. Ubuntu Jammy has clang v14 and Arch Linux has clang v17. Their formatter always output different result. I'm still looking for a solution how to make .clang-format be universal. Because this problem also affects Debian users since they prefer to stay on most stable version.

For the CMake, this is my mistake. I supposed to consider to use STREQUAL instead of EQUAL due to compatibility issue.

[Thor-x86]

I'll wait for your comment about this.

It's going to be a new PR in the future. For now, you can safely merge the changes.

[HidenoriMatsubayashi]

Okay, thank you so much.