AssetInfo implementations

[Rhaki]

This pull request would add some useful implementations to AssetInfo:

• Added #[derive(Eq, PartialOrd, Ord, Hash)] to AssetInfoBase<T: AddressLike> allowing to use AssetInfoBase as key for both HashMap and BTreeMap;
• Implemented fn inner() for AssetInfo which return the inner cw20 addr or denom wrapped within;
• Prefix and Suffix types have been changed from () - () to String - String on PrimaryKey implementation for AssetInfo. This allow to iterate over a Map<AssetInfo, T> by prefix that can be cw20: or native: (colon is required to match with the first key generated in fn key() on PrimaryKey implementation);
• Tests have been created to assert these implementations.

[Rhaki]

A New commit with review changes has been pushed

[piobab]

Thanks for update. LGTM

[Rhaki]

@piobab Is possible to release the new version also on Crates.io?

[piobab]

@Rhaki I can publish as 3.1.0 version. Makes sense?

[Rhaki]

@piobab LGTM

[piobab]

@Rhaki please take a look #23

[Rhaki]

@piobab LGTM!
I could have some useful features that could be added, in case i'll open a new PR based also on the usability of the latest features added with this PR, try to add all of them in a single PR

[piobab]

Thx for contribution! Great job! New version published in crates.io