feat: Jan Server, API and decoupled clients

[louis-menlo]

Key updates

• Shared node module from core that shared logics between node instances
• Remove manual typed FS handlers and logics, IPC & REST APIs for this should be proxied automatically.
• Extensions APIs, allow client to install / use remote extensions hosted by node instance
• Static files serve so client can access ~/jan remotely e.g. import extensions / JS files remotely
• Request from extensions routed to 1337, no longer IPC
• Nitro & monitoring work
• Localhost 1337 APIs
• Proxy /chat/completion
• ( Deprecated ) feat: [Jan Server] fs watch, process, download state sync #1117

Refactor - Enhancement

• refactor: shared server module between node instances #1050
• refactor: exported modules from core should be mapped with their types #1171
• FS watchdog (any further memory problem?)
• ES node module? currently can't import but just require

[louis-menlo]

@vuonghoainam testing env key, will refactor later

export EXTENSION_ROOT=/Users/$(whoami)/jan/extensions

yarn dev

curl --request GET \
--url http://localhost:1337/v1/threads \
--header 'User-Agent: insomnia/8.4.5'

Please help on /chat/completions