feat: asset registry refactored

[enthusiastmartin]

New pallet-registry added.

It is a rework of original and very simple asset-registry pallet. This new implementation attempts to be more robust and easier to use.

New Features compared to previous implementation includes:

• dispatchables for registering and updating assets
• string limit for asset name
• native locations ( use for xcm ) - it possible to store an origin location of an asset. This can be used in xcm currency/location conversions ( no need to specify/hard-code it in runtime)
• asset detail and metadata
• better handling of 'next asset id' - our asset registry uses sequential ids which is assigned for each newly registered asset.

[codecov]

Codecov Report

Merging #124 (c911440) into master (a6db44f) will increase coverage by 0.42%.
The diff coverage is 89.47%.

@@            Coverage Diff             @@
##           master     #124      +/-   ##
==========================================
+ Coverage   85.66%   86.08%   +0.42%     
==========================================
  Files          20       21       +1     
  Lines        1911     2048     +137     
==========================================
+ Hits         1637     1763     +126     
- Misses        274      285      +11     

Impacted Files	Coverage Δ
primitives/src/traits.rs	71.42% <50.00%> (-28.58%)	⬇️
pallets/asset-registry/src/lib.rs	88.67% <87.87%> (+12.48%)	⬆️
pallets/asset-registry/src/benchmarking.rs	100.00% <100.00%> (ø)
pallets/xyk/src/lib.rs	83.71% <100.00%> (ø)

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[mrq1911]

LGTM