Implement As_x for Caller, Source, Mission and Server

[jokoho48]

• Title

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 24 lines in your changes missing coverage. Please review.

Project coverage is 89.9%. Comparing base (4bd3476) to head (4436380).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
arma-rs/src/context/call.rs	0.0%	24 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
arma-rs/src/context/call.rs	74.4% <0.0%> (-25.6%)	⬇️