Structure and modernize bridgedescs module
- All parsing should be delegated to metrics-lib code.
- Create 'BridgeMain'.
Current picture: BridgeSnapshotReader only has a constructor of more than 200 lines of code. BridgeDescriptorParser actually only determines the descriptor type and SanitizedBridgesWriter performes parsing and obfuscation.
+------------------------+
| SanitizedBridgesWriter |
+---o----+---------------+
--/ /- \
--/ /- \
--/ /- \
--/ /- \
--/ /- +------+----------------+
+----------+---------o---+ | BridgeSnapshotReader |
| BridgeDescriptorParser +--------------o-----------------------+
+------------------------+
X o----------+ Y : X holds a Y reference somewhere