v3.0.0-rc1

Version 3.0.0-rc1 cleans up a lot of internal devkit architecture, specifically around building and simulating games. Note that most new functionality requires the use of corresponding devkit-core version >= v3.0.0-rc1.

• --single-port-only is now the default (and only option) for devkit serve. Games were previously hosted on different ports, complicating the internal architecture. Now all games are served on the same port, default 9200.
• --separate-build-process is now the default (and only option) for simulated builds. Builds for the simulator previously ran in the same process as the main devkit serve, causing the main server to die on errors. This adds robustness to the simulator and helps prevent build data from leaking between builds. This also allows the simulator to easily interrupt currently running builds by terminating the subprocess.
• various speed and memory improvements - the devkit cli starts up faster
• Introduces devkit-view-inspector and devkit-simulator-client modules for the simulator. Previously, the code for this functionality was tightly coupled with devkit-core and versioned with devkit-core. The corresponding UI lives in devkit, so by versioning this code with devkit, we can help ensure it doesn't break. These modules also consume the new devkit extensions api for extending the simulator functionality.
• various bug fixes and improvements to the devkit install command