feat: impl `throws` in services via `gr_panic` syscall, update `meta`, code generation

[vobradovich]

File Location(s)

No response

Proposal

Impl throws in services via gr_panic syscall, update meta, code generation

• add Syscall::panic method to use gr_panic
• call Syscall::panic with Error payload (and header?)
• add throws type to Command/Query meta as third parameter
• update macros, client code gen