Remove impl AsObjectArg<T> for Gd<T> values #1718

Job	Run time
cargo-deny-machete	14s
clippy	1m 47s
doc-lints	44s
godot-itest (macos-x86)	3m 39s
godot-itest (macos-double-x86)	4m 11s
miri-test	1m 38s
proptest	20s
license-guard	28s
godot-itest (macos-x86-4.2)	2m 31s
godot-itest (macos-arm)	1m 30s
run-examples	1m 11s
rustfmt	29s
godot-itest (macos-arm-4.2)	57s
unit-test (macos)	1m 24s
godot-itest (windows)	3m 34s
unit-test (windows)	4m 24s
godot-itest (windows-double)	3m 29s
unit-test (linux)	2m 27s
godot-itest (windows-4.2)	2m 32s
unit-test (linux-minimal-deps)	1m 46s
godot-itest (linux-full)	2m 21s
unit-test (linux-msrv)	2m 21s
godot-itest (linux-double-lazy)	2m 6s
godot-itest (linux-features-experimental)	1m 30s
godot-itest (linux-release)	1m 22s
godot-itest (linux-4.3)	1m 11s
godot-itest (linux-4.2)	1m 5s
godot-itest (linux-memcheck-nightly)	2m 22s
godot-itest (linux-memcheck-4.1)	1m 44s
ci-status	0s
	55m 17s

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