Open Source DefiLlama TVL models

[sydneynotthecity]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with the jira ticket associated with the PR.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated the docs and README with the added features, breaking changes, new instructions on how to use the repository.

Release planning

• I've decided if this PR requires a new major/minor/patch version accordingly to
  semver, and I've changed the name of the BRANCH to major/* , minor/* or patch/* .

What

Expose the aggregation methodology for reporting Stellar DEX TVL to DefiLlama.

Stellar RPC lacks the ability to query information at the asset or wallet level. The querier must index the specific asset + address combination in order to fetch token information like balance. It is much simpler to calculate and report TVL using Hubble

Why

Make the TVL logic public so that it is auditable by the ecosystem

Known limitations

We are limited to only reporting TVL for assets that are priced in CoinGecko. For assets to be included in the measure, they must have pricing data in CoinGecko first.

Also updated all yaml configs to use the tag data_tests instead of tests.