MCAP `MessageLayers` should only look at relevant chunks

[grtlr]

Currently, we still iterate over an entire MCAP file to retrieve all the messages that are relevant for a given dyn MessageLayer. We should abstract of the ::mcap::Summary and mcap_bytes to allow indexed access + filtering of the MCAP file.

We should be able to:

• Filter by topic
• Filter by time range

Each MessageLayer should specify the encoding or schema of messages that it is interested in and then get presented only those messages. This is required large MCAP files, as well as presenting more useful errors on a per-layer basis.

[oceanusxiv]

@grtlr Hi, I'm curious, is this being actively worked on right now? If not, I might be interested in taking a stab at this since this is very useful or me.