Add wasmi_collections crate

[Robbepop]

This replaces the old wasmi_arena crate with a more versatile and general wasmi_collections crate.
Inspired by wasmparser's upcoming collections module found here: bytecodealliance/wasm-tools#1521

This allows Wasmi to be run as efficiently as possible in all supported environments via the new no-hash-maps crate feature which can be used to toggle HashMap or BTreeMap usage within the entire Wasmi crate.

[codecov]

Codecov Report

Attention: Patch coverage is 8.50440% with 312 lines in your changes are missing coverage. Please review.

Project coverage is 80.74%. Comparing base (492be5a) to head (818994f).

Files	Patch %	Lines
crates/collections/src/map.rs	8.63%	127 Missing ⚠️
crates/collections/src/set.rs	0.00%	87 Missing ⚠️
crates/collections/src/string_interner/detail.rs	0.00%	62 Missing ⚠️
crates/collections/src/hash.rs	47.05%	18 Missing ⚠️
crates/collections/src/string_interner.rs	0.00%	18 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1007      +/-   ##
==========================================
- Coverage   81.75%   80.74%   -1.01%     
==========================================
  Files         264      269       +5     
  Lines       24445    24785     +340     
==========================================
+ Hits        19984    20012      +28     
- Misses       4461     4773     +312     

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