[Enhancement] Add IMF Financial Soundness Indicators Set

[deeleeramone]

1. Why?:

   • This PR adds 2200+ symbols to the IMFs list of available_indicators, from the Financial Soundness Indicators.
   • Data is from this set: https://data.imf.org/?sk=51b096fa-2cd2-40c2-8d09-0699cc1764da

The Financial Soundness Indicators (FSIs) were developed by the IMF, together with the international community, with the aim of supporting macroprudential analysis and assessing strengths and vulnerabilities of financial systems.

The website, hosted by the Statistics Department of the IMF, disseminates data and metadata on selected FSIs provided by participating countries. For a description of the various FSIs, as well as the consolidation basis, consolidation adjustments, and accounting rules followed, please refer to the “Concepts and Definitions” document (http://data.imf.org/?sk=9F855EAE-C765-405E-9C9A-A9DC2C1FEE47). The Statistics Department will steadily increase the number of countries reporting FSIs for dissemination on this site.

Reporting countries compile FSI data presented on this website by using different methodologies, which may also vary for different points in time for the same country. Users are advised to consult the accompanying metadata (http://data.imf.org/?sk=9F855EAE-C765-405E-9C9A-A9DC2C1FEE47) to conduct more meaningful cross-country comparisons or to assess the evolution of a given FSI for any of the countries.

2. What?:

   • Adds this into the existing functions:
     • obb.economy.available_indicators
       • Adds a "query" parameter to filter down the complete list (static file)
     • obb.economy.indicators
       • Any symbol from FSI, and the existing IRFCL, sets can be combined and with multiple countries.
       • "presets" added to return groups of series.
         • 'fsi_core': The core Financial Soundness Indicators. Compatible with multiple countries.
         • 'fsi_core_underlying': The core FSIs underlying series data. Not compatible with country='all'.
         • 'fsi_encouraged_set': The encouraged set of Financial Soundness Indicators. Not compatible with country='all'.
         • 'fsi_other': The other Financial Soundness Indicators. Not compatible with country='all'.
         • 'fsi_balance_sheets': Data categorized as Balance Sheets and Income Statements. Not compatible with country='all'.
         • 'fsi_all': All the Financial Soundness Indicators. Not compatible with multiple countries.
         • 137 countries have reported some data since the beginning of 2023

3. Impact:

   • Expands the macroeconomic data.
   • Increases the complexity of the endpoint, which is inevitably going to keep expanding.
   • Number of symbols is somewhat exaggerated by their being three symbols for one item, where it represents a currency - Euros, US Dollars, Domestic Currency.

4. Testing Done:

   • Using the presets, only 'fsi_core' is compatible with All-Countries Mode
     • obb.economy.indicators(symbol="fsi_core", provider="imf")
   • obb.economy.indicators(symbol="gold_reserves,fsi_core", provider="imf")
   • `obb.economy.indicators(symbol="FSLT_PT,RAFAGOLDV_OZT", country="germany,fr,china,gb", start_date="2023-01-01", provider="imf")
   • obb.economy.available_indicators(provider="imf", query="household;debt;principal")

'order', 'level', 'children' are applicable to the fsi_core and fsi_encouraged_set presets.
These two return values as a percent, so they are comparable between countries.