Encoder/decoder revamp

[digorithm]

The Sway compiler is going through a long-discussed revamp of its encoder/decoder scheme, eventually leading to an intermediary representation that both the SDK and the compiler will target.

Tasks:

1. __log outputting encoded values sway#5306
2. feat!: add support for experimental encoding in logs #1259
3. Serialization and encoding/decoding sway#4769
4. fix!: encoding capacity overflow #1249
5. Support new encoder/decoder for contracts #1278
6. Support new encoder/decoder for scripts and predicates #1279

This will enable, once and for all, the support of nested heap types, solving many open issues related to this problem, such as:

1. Decoding string slices from logs #1151
2. RawSlice as arguments in scripts #1152
3. String slices support #1158
4. Arbitrary nesting of heap types in contract returns #1046
5. feat: enable Bytes logging in contracts #901
6. feat: enable Vec logging in contracts #898
7. feat: support heap types return from scripts #866

As seen above, many issues stem from a lack of support for nested heap types. This new encoding/decoding scheme implemented inside the Sway compiler will enable this.

[hal3e]

We have several issues here that were solved with the experimental log encoding PR. Should we close them or keep them until we have this stabilized ?

[digorithm]

@hal3e That's true. I'll check which ones of those were resolved and close them.

[digorithm]

Closing this as most of the work has been done, and the leftovers will be pushed as a follow-up work.