Add ApplicationDataValueWrite::SignedInt and UnsignedInt variants.

[de-vri-es]

This PR adds a SignedInt and UnsignedInt variants for ApplicationDataValueWrite to support writing integer values.

[ninjasource]

Hey, thanks for your contribution. I really appreciate it. Can you please just write a short description of what you have added so that I don't have to read the code to figure it out. Just a bit more detail than you put in. This will help me answer two questions. Is this change here to get some proprietary device to work that won't benefit anyone else? Is the code written by an human? (it changes the way I review it). No offense intended btw, just the nature of things these days. :)

[de-vri-es]

No offense taken. It's all written by me personally. No AI.

The changes:

• ApplicationDataValue:
  • The UnsignedInt variant now holds a u64 instead of a u32.
  • The SignedInt variant was added, which holds an i64.
• ApplicationDataValueWrite
  • Added UnsignedInt and SignedInt variants, holding a u64 and i64 respectively.
• In common/helpers.rs I've refactored integer encoding and decoding. It now always encodes int as the smallest value (as technically required by the standard), and it also implements parsing integers which are 5, 6 or 7 bytes in length.
  • I've added some tests for counting the number of bytes to be skipped when encoding.
• I've disabled the simple module when the alloc feature is disabled, because it doesn't compile. I couldn't see an easy fix, otherwise I would have implemented it.

This is not for any specific quirk in a proprietary device, but to extend support for standard integer properties: reading signed values, writing signed and unsigned values, and decoding more valid integer encodings.

[ninjasource]

Thanks for your contribution, looks good! I really appreciate it.

[de-vri-es]

Thanks for the quick review!