dApp Staking v3 - Improved Tier Thresholds Calculation

[Dinonard]

Description

In the current implementation, tier thresholds can either be fixed or dynamic.
The threshold amount is expressed in a total value, irrelevant of the total issuance or any other parameters.
This means it will have to be adjusted sometime in the future, when issuance becomes larger.

To improve this in the future, we should consider alternatives where threshold is adjusted to the total issuance, and possibly other factors.

Another factor to consider is number of tier slots, in relation to tier threshold. This is important to "visualize" (and model in a spreadsheet) to understand how much dApps can we "really" support.