Fix Issue 20869 - move is overly trusting of opPostMove

[MoonlightSentinel]

Remove the manual check whether move is @safe and instead let the compiler do the attribute interference by adding appropriate @trusted blocks.

Note: I could've extend the current checks trustedMoveImpl but that could easily miss other corner cases.

TLDR: Only use @trusted when necessary

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20869	enhancement	std.algorithm.mutation : move is overly trusting of opPostMove

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#7502"

[thewilsonator]

Please target stable.

[wilzbach]

Looks great!

[MoonlightSentinel]

Please target stable.

Is stable broken?

std/math.d(4423): Error: `core.math.yl2x` called with argument types `(real, int)` matches both:
../druntime/import/core/math.d(167):     `core.math.yl2x(float x, float y)`
and:
../druntime/import/core/math.d(169):     `core.math.yl2x(real x, real y)`
posix.mak:326: recipe for target 'generated/linux/debug/64/libphobos2.a' failed

[MoonlightSentinel]

Rebased to master because this might break code relying on the invalid @trusted (and stable seems to be broken ATM).

[n8sh]

Is stable broken?

The broken compilation is because it's using stable phobos with master druntime instead of stable with stable.