Set festivald & festival-cli as unmaintained

[hinto-janai]

Why

festivald and festival-cli were both created because "why not?".

A majority of the internal code was already written and explicitly created to be usable with multiple frontends.

Nothing is wrong with either of them, but:

1. I do not use them personally
2. They make making changes to the internals difficult

This prevents changes from occurring in the main frontend: festival-gui.

What now

Both festivald & festival-cli will be officially "unmaintained".

The only released v1.0.0 binaries will still work, but they will not receive updates.

The code for both these projects will continue to exist in the repository, and will still be able to be compiled with:

# festivald
git checkout daemon-v1.0.0
cargo build --release --package festivald

# festival-cli
git checkout cli-v1.0.0
cargo build --release --package festival-cli

Future

I have plans for separating major parts of shukusai (the internals) into many different libraries.

festivald & festival-cli may reappear, using these new libraries in a v2.0.0 when I eventually write them... someday.