Rewrite of "deploy" command to use new phar generation

[stloyd]

After introducing box (#175), it is a good choice to directly rewrite DeployCommand. Ideally, we can automatically package single executable SPC files for different platforms and upload them when releasing a new version:

Roadmap:

• Use the command bin/spc download --all to download dependencies
• Compile the phpmicro SAPI with minimal extension required by static-php-cli itself: bin/spc build pcntl,posix,mbstring,tokenizer,phar --build-micro
• Package project: vendor/bin/box compile
• Generate executable binary: bin/spc micro:combine spc.phar
• Upload to release artifacts: spc-macos-x86_64.tar.gz