Code restructuring - Resolving technical debt

[marenz2569]

• Move implementation of ring buffer of hashes for deduplication into src/filter/mod.rs
• Return an error if we cannot process telegrams. Here errors are ignored: https://github.com/dump-dvb/data-accumulator/blob/9bcb76a660332325666fb4516934d4537629b436/src/processor/mod.rs#L100
• Deduplication has to be done for each region individually, otherwise we might loose telegrams
• ReducedTelegrams is defined in multiple locations with different members https://github.com/dump-dvb/data-accumulator/blob/3276bfac76e8cefd6a6aa98018b88774642df06e/src/filter/telegram.rs#L30 https://github.com/dump-dvb/data-accumulator/blob/18f4a20d66c41c0e4ceeb8c0cf83295a420ec3f0/proto/telegram.proto#L9
• Open discussion: Implementation of the deduplication. Should we use a fixed sized ring buffer or check for telegrams in the same time region, e.g. less than 5 seconds apart.
• Open discussion: Where do we add the timestamp?
• Open discussion: Code flow. Idea: receive -> parse telegrams -> deduplication for each region -> storage backend. Right now the second and third step is swapped around.