Inconsistent Prettier Formatting

[ssande-fwd]

Describe the bug
I get extensive formatting edits to existing code when I run buildspecs in jacdac-docs using VS Code.

To Reproduce
Steps to reproduce the behavior:

1. Set up jacdac-docs in VS Code.
2. Run "yarn buildspecs".
3. Observe changes that were made to pxt-jacdac, for example.

Expected behavior
I expect that there will be no formatting of existing code since there are .prettierc files and prettier runs every time you run buildspecs.

Additional Context
If I change trailingComma to none to avoid some of the edits I instead get edits on different files where there are no trailing commas.