As a dev, I want to have better control over the themes and stylings of IDE2

[kittaakos]

Describe the request

IDE2 comes with two primary themes: Arduino Light and Arduino Dark. The themes define all colors for every UI element, including the coloring in the editors. These files are:

• dark.color-theme.json
• default.color-theme.json

The IDE2 themes have flaws here and there; a few of them are the followings:

• Un-pulled remote sketch is barely visible with the dark theme #1578
• "Edit in settings.json" link invisible when using "Light (Arduino)" theme #1537
• Improve the selection color in the terminal #1400
• Error line editor decorator not visible when using "High Contrast" themes #1271
• Improve contrast of cursor color in "Dark (Arduino)" theme #1251
• Use a more readable color for "Output" view stderr text in the "Light (Arduino)" theme #1087

Devs cannot modify the theme JSON files manually because they're generated from a JSON file that is not part of this repository and is not under version control.

When somebody modifies the god JSON file, GH Actions automatically creates a PR with the derived theme JSON changes. See an example here or here. We can improve the following workflow.

• Add documentation on what's happening and how to change the god JSON file to trigger the automatic PR.
• When the theme update auto PR arrives, it does not contain the original author of the god JSON file. The auto-PR carries no information about why the change was made. (We could consider moving the god JSON file under version control)
• Finally, as a dev, I would like to make tiny color changes and necessarily depend on others.

Describe the current behavior

n/a

Arduino IDE version

d6a4b0f

Operating system

macOS

Operating system version

12.5.1

Additional context

No response

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the latest nightly build
• My request contains all necessary details