fix: oracle RV audit feedback

[apopiak]

Various small improvements.

• add Short period to all_periods
• remove MAX_UNIQUE_ENTRIES and trades_estimation.py
• rename timestamp field to updated_at and add constructor
• add inverted function to Ratio
• add some comments

[github-actions]

Crate versions that have been updated:

• hydra-dx-math: v7.1.0 -> v7.2.0
• pallet-ema-oracle: v1.0.3 -> v1.1.0
• hydradx-traits: v2.3.1 -> v2.4.0

Runtime version has not been increased.

[dmoka]

In the common package, there is an adapter called OraclePriceProviderAdapterForOmnipool, which implements the trait PriceOracle, used in DCA pallet.

This adapter gets the price for an arbitrary asset pair TKN1 - TKN2, by multiplying the results of nominators and denominators for TKN1-LRNA, LRNA-TKN2, resulting in TKN1 - TKN2 asset pair price.

I wonder whether we need to change something there due to this current PR. What do you think?

[codecov]

Codecov Report

Patch coverage: 78.26% and project coverage change: -0.03 ⚠️

Comparison is base (cdebe05) 64.66% compared to head (827683c) 64.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #617      +/-   ##
==========================================
- Coverage   64.66%   64.63%   -0.03%     
==========================================
  Files         130      130              
  Lines        9446     9450       +4     
==========================================
  Hits         6108     6108              
- Misses       3338     3342       +4     

Impacted Files	Coverage Δ
math/src/ratio.rs	69.44% <0.00%> (-8.69%)	⬇️
traits/src/oracle.rs	56.89% <ø> (ø)
pallets/ema-oracle/src/types.rs	91.66% <90.90%> (ø)
pallets/ema-oracle/src/benchmarking.rs	98.75% <100.00%> (ø)
pallets/ema-oracle/src/lib.rs	87.91% <100.00%> (ø)

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[apopiak]

I wonder whether we need to change something there due to this current PR. What do you think?

As discussed offline, not applicable for this PR.