no_std Tidy-up

[bushrat011899]

Objective

• Split off low-controversy component of Extend no_std Support #263

Solution

Refer to individual commits for further details

• Added rust-version = "1.81.0" to all crates, making it easier to maintain MSRV going forward. Exact version chosen for compatibility with core::error::Error.
• Switched to core implicit prelude instead of conditionally changing the prelude based on a possible std feature. This makes migrating currently std-only features to no_std easier in the future.
• Updated CI to test all no_std compatible features, not just --no-default-features.
• Updated zune-core to allow serde feature in no_std
• Updated zune-inflate to remove std feature (unused)
• Updated zune-jpeg to remove std feature (unused)
• Updated zune-qoi to remove std feature (unused)
• Updated zune-bmp to remove std feature (unused), opting for adding std feature in dev-dependencies instead
• Made zune-gif no_std (only minor changes required)
• Updated zune-jpegxl to explicitly require std in the threads feature

[etemesi254]

This makes us lose runtime detection so may be slower see docs on https://docs.rs/simd-adler32/latest/simd_adler32/

Any reason why it was removed

[etemesi254]

ping on comment above

[CompeyDev]

Seems abandoned, it would be extremely handy to have at the very least core errors. It would also be worth using cpufeatures for runtime detections, instead of gating it purely behind std presence.