[Feature] Add IMF Provider Extension and Extend obb.economic.indicators

[deeleeramone]

1. Why?:

   • The IMF provides a public API for their database, and time series data is widely used across macroeconomics.
   • No credentials are required.
   • Reference

2. What?:

   • New provider extension: openbb-imf
   • Extends endpoints:
     • obb.economy.available_indicators
       • Serviced by a static JSON file.
     • obb.economy.indicators
       • Currently only supports data from the International Reserves and Foreign Currency Liquidity collection.
   • The data is returned in a flat-format suitable for pivot tables and SQL.

3. Impact:

   • The symbol parameter in obb.economy.indicators has been moved to provider definitions to allow varying docstrings with helpful information about the symbols which will vary by provider.

4. Testing Done:

   • Unit/Integration tests.
   • Sampled a large cross section of data

res = obb.economy.indicators(
    symbol="RAMFDA_USD",  # This is the symbol called by the preset 'derivative_assets'
    provider="imf",
    country="all",
    frequency="month",
    start_date="2015-01-01",
)
df = (
    res.to_df(index=None)
    .pivot_table(
        index="date",
        columns=["symbol", "country"],
        values="value",
        observed=True,
        sort=False,
    )
    .RAMFDA_USD
)
chart_params = {
    "x": "date",
    "y": ["Japan", "China", "Mexico", "Brazil"],
    "index": "date",
    "barmode": "overlay",
    "title": "Financial Derivative Assets (Net, Marked to Market)",
    "ytitle": "Nominal Value In Millions of USD",
    "layout_kwargs": {
        "legend": {
            "orientation": "v",
            "y": 0.95,
            "x": -0.01,
            "xanchor": "right",
            "yanchor": "top",
        }
    },
    "external": True,
}
fig = res.charting.create_bar_chart(data=df.reset_index(), **chart_params)
for trace in fig.data:
    trace.update(hovertemplate="<b>$</b>%{y:,.1f} M", opacity=0.75, width=0.8)
fig.show()