[Task]: Update `"efiapi"` event, timer, and tpl functionality to be unsafe

[berlin-with0ut-return]

Request Description

As of r_efi 6.0.0, most "efiapi" function types have been marked unsafe. This tracks a sub-issue to make the following functions unsafe and appropriately comment on safety requirements:

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I have chosen to group these due by the UEFI spec functionality groupings. See https://uefi.org/specs/UEFI/2.9_A/07_Services_Boot_Services.html

Are you going to make the change?

I will make the change

Do you need maintainer feedback?

No maintainer feedback needed

Anything else?

No response