jlcparts-based parts library

[ducky64]

A set of parts libraries based on data available from https://github.com/yaqwsx/jlcparts

JLC no longer (well, hasn't for a few years now) makes their entire parts library available by CSV, and the current parts table is starting to get outdated with parts no longer available or basic parts. jlcparts seems to be able to get an up-to-date library as well as do some parsing of parametric parts.

Since the data here isn't deterministic, this is strictly opt-in; all test boards will continue to be based on the included CSV. By nature this won't be as well-tested.

To use these parts:

1. clone jlcparts, download the cached parts list and build its tables (according to its readme)
2. in the top-level board design file, add JlcPartsBase.config_root_dir("/path/to/jlcparts-repo/web/public/data/")
3. in the top-level design, add JlcPartsRefinements to the superclass list before (takes priority over) other refinements

so if this was done on the SMU example, it would look like:

import ...
JlcPartsBase.config_root_dir(".../jlcparts/web/public/data/")
...
class UsbSourceMeasure(JlcPartsRefinements, JlcBoardTop):
  def contents(self) -> None:
    ...

Other changes

• Add green-yellow to TableLed, different than a more intense green I guess
• Add TableLed
• Internal semantics: these are now exact even when no tolerance is specified: FerriteBead.DC_RESISTANCE, Fet.RDS_ON, Inductor.DC_RESISTANCE,
• Pin dependency versions in requirements.txt