Remove alloc and bytes dependency

[qwerty19106]

Mavlink can be used in no_std mode, for example for thumbv7em-none-eabihf target (Cortex-M microcontrollers).
Heap usage is very bad idea for microcontrollers. It introduces uncontrollable latency and unacceptable for some tasks such as motor control.

1. Mavlink frame has fixed size: up to 263 bytes for Mavlink V1, up to 280 bytes for Mavlink V2 (MAVLink Packet Format).
   I replaced all std::Vec (alloc::Vec) to stack allocated heapless::Vec.

2. The struct bytes::BytesMut is no support no_std mode. Its API and code very requires on std::Vec.
   Moreover BytesMut use BufMut API with chunk_mut method. Due to BytesMut::put_* and BytesMut::get_* methods use while cycle with code, which can not be optimized by compiler (loop unwinding). It is very slow.
   Therefore I replace bytes::BytesMut on two small (320 lines summary) and fast structs Bytes and BytesMut with analoguous API.

3. I replaced all String usages to &'static str.

It is breaking changes, but it increase perfomance in std mode too.

[Erk-]

Some small things, this is a nice change overall

[qwerty19106]

It is ready to review.

[qwerty19106]

Embedded example was been updated too.

Cargo compile crc-any dependency with build-dependencies features for this example. Thus example can not been compiled due to alloc dependency.
It is very ugly! I add default-features = false into crc-any build-dependency to prevent it.

[patrickelectric]

@qwerty19106 please check CI

[qwerty19106]

The cargo fmt errors are fixed.

[patrickelectric]

The cargo fmt errors are fixed.

You need to rebase over master since the branch has conflicts now.

[qwerty19106]

Rebased

[patrickelectric]

We can let as it's for now, but for future PRs, you should apply the rustfmt changes on their specific commits.

[patrickelectric]

And thanks for the contribution!