Separate CLI package

[verytactical]

Issues

• fs, path or other node-specific modules might be accidentally imported, and browser version would have to mock them. There is already a VirtualFileSystem that should be the only interface to file system.
• __dirname shouldn't be used outside of *.build.ts and *.spec.ts files. Compiler doesn't have to know where its sources are.

To do

• Create separate package with compiler internals (@tact-lang/core?)
• src/vfs/createNodeFileSystem.ts should be left in @tact-lang/compiler.
• Ensure only posix (/) paths are passed to internals package.
• Remove @types/node dependency from internals package.
• Ban __dirname with eslint.

[anton-trunov]

(@tact-lang/language?)

@tact-lang/core ?