Partial conversion to `CppRef<T>` everywhere #2303

Job	Run time
Address Sanitizer	20m 20s
Examples Rust nightly	49s
Examples Rust beta	42s
Examples Rust stable	48s
Clippy	22s
Examples macOS	53s
Test forcing wrapper generation	44s
Format	6s
Examples Windows (gnu)	2m 45s
Examples Windows (msvc)	2m 45s
Outdated	7s
Docs	1m 14s
Test Rust nightly	9m 2s
Test Rust beta	1m 19s
Test Rust stable	1m 29s
Test macOS	13m 34s
Test Windows (msvc)	18m 58s
	1h 15m 57s

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