Set IAVL config

[facs95]

Description

the configuration can be changed in app.toml

# IavlCacheSize set the size of the iavl tree cache.
# Default cache size is 50mb.
iavl-cache-size = 781250

# IAVLDisableFastNode enables or disables the fast node feature of IAVL.
# Default is true.
iavl-disable-fastnode = true

PR done initially by @giansalex but opening because of time constraints 🙏

Closes: #XXX

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