* include pebble as built-in plugin

Pebble provides a high-performance alternative to leveldb as the datastore, and will serve as a replacement for badger1.

There are a number of tuning parameters available for tuning pebble's performance to your specific needs. Default values are used for any that are not configured or are set to the parameter's zero-value.

Requires https://github.com/ipfs/go-ds-pebble/pull/39

Closes #10347

* docs: remove mention of ipfs-ds-convert. Rationale: https://github.com/ipfs/ipfs-ds-convert/issues/50
* docs: pebbleds profile
* test: meaningful t0025-datastores.sh
* Update config/init.go
* Update docs/config.md
* Do not hard-code zero values into pebble config