Fix Issue 20346 - std.uuid does not compile with checkaction=context

[MoonlightSentinel]

Marking all parameters as const additionally reduces the amount of instantiations of miniFormat

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	20346	normal	std.uuid does not compile with checkaction=context

Testing this PR locally

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

dub fetch digger
dub run digger -- build "master + druntime#2846"

[wilzbach]

Thanks!
Though we should check the actual generated string.

[MoonlightSentinel]

@wilzbach Dont merge yet, i will add another test concerning the correct toString selection

[MoonlightSentinel]

@wilzbach Done