Add ability to slice data into unequal/user defined bins

Add ability for sequences subcommand to use unequal bins. For example, given a trigger rep rate of 20us, we want to slice the data into 10ns bins for the first 1000ns, then 1us bins for the remaining 19us.

Start by locating the sequences subcommand and its existing binning implementation. Check how the trigger repetition rate is used, then define the user-facing input for unequal bins and verify that the output uses 10ns bins for the first 1000ns and 1us bins for the remaining 19us.

Written by the indexing model from the issue text.