Add functionality required for the GUI

[alexhroom]

This PR adds some extra functionality that was needed for the GUI:

• Access to checking whether the cache is valid
• Getting the full list of log names
• Getting the list of filter time intervals (for drawing green boxes on the GUI)
• Getting the filters in some readable (JSON) format for updating tables
• Clearing all filters.

Also fixes a bug where NexusData.get_frame_times() returned the frame start times as 32-bit integers, which is not big enough for the data and was causing issues with time filter bounds.

Fixes #119

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👋 Hi, @alexhroom,

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[github-actions]

👋 Hi, @alexhroom,

Conflicts have been detected against the base branch. Please rebase your branch against the base branch.

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This message is automatically generated by prince-chrismc/label-merge-conflicts-action so don't hesitate to report issues/improvements there.

[AnthonyLim23]

I think its better testing this in the GUI. However, I wonder if it would might make more sense to add some of this code to the GUI repo, then users wont get it as part of the backend. I am only thinking this because if you picked the GUI to install you are unlikely to run the Python directly and the code is very GUI specific.

[alexhroom]

@AnthonyLim23 I disagree:

• clear_filters is something users may well want to do in the API
• _dict is fair enough, but it needs to be written in Rust as it is accessing parts of the code that aren't accessible from the Python. same for data_changed and getting sample_log_times. So if we wanted to add these to the GUI repo we'd need to:
  • upload MNeuEventLib to crates.io as a pure Rust crate;
  • create an MNeuEventGUI Rust extension which takes MNeuEventLib as a cargo dependency;
  • add these features to the Rust extension.
    which I actually think is more complicated than just having them be here.
• finally, _get_filter_times actually needs to be used by the backend to implement the functionality added in Intersect log weights for different logs #121 (hence why that one is stacked on top of this one) so if we re-implemented it in the GUI we would just be duplicating code.

[AnthonyLim23]

That all make sense to me. I didn't appreciate the extra effort needed with the crate for what is a small change.

[alexhroom]

@AnthonyLim23 the 'lower effort' alternative to that crate stuff would be if we exposed all the internal data and methods of the code to the Python API, and implemented these methods in Python in the GUI repository. which a.) doesn't fix our problem because we would still have a load of GUI-specific attribute code, and b.) makes the GUI slower because it's doing all this in Python instead of Rust.