Speed up output - Githubissues

Some changes to speed up writing output files, specifically flowveldepth netcdf for runs with many timesteps.

Enable t-route to use nex-* file as a forcing file, and only convert/write parquet files if binary_nexus_file_folder is provided.

Additions

[ ] PR has an informative and human-readable title
[ ] Changes are limited to a single goal (no scope creep)
[ ] Code can be automatically merged (no conflicts)
[ ] Code follows project standards (link if applicable)
[ ] Passes all existing automated tests
[ ] Any change in functionality is tested
[ ] New functions are documented (with a description, list of inputs, and expected output)
[ ] Placeholder code is flagged / future todos are captured in comments
[ ] Visually tested in supported browsers and devices (see checklist below :point_down:)
[ ] Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
[ ] Reviewers requested with the Reviewers tool :arrow_right: