[PIBD_IMPL] BitmapAccumulator Serialization Fix (mimblewimble#3705)

* fix for writing / calculating incorrect length for negative indices

* update capabilities with new version of PIBD hist

* remove incorrect comment

* fix capabilities flag, trace output

* test fix

prepare branch for 5.1.2 release

Change connection name for CI Release (mimblewimble#3653)

Bump version for v5.0.4 release (mimblewimble#3604)

Bump version for v5.0.3 release (mimblewimble#3601)

Bump version to v5.0.2 (mimblewimble#3599)