Add a counter to log the range of pruned blocks
Implement autoprune

This mode introduces a configuration parameter to keep block files at less than a fixed amount of MB
Check the size of files reported on memory, and compare it with the size registered on disk.
Fail if the prefix passed to RemoveDiskFile is unknown.
Set size to 0 in block files info after removing the files.
Do not try to read the files if their size is zero.
Do not warn about size measure differences during IBD, reindex and loading of blocks.

In those cases the differences are somewhat expected.
Parameterize the acceptable ratio of size divergence, and adjust it for IBD, reindex and loading.
Always log ratio to Monitor its behavior.
Change headers first fix.
Only check range of nPrune if it's set.