feat: added configuration default fill color and default stroke color

[zxuanhong]

1. Added configuration default fill color and default stroke color.This makes some special environment display better(such as dark mode).This configuration is consistent with bpmn js
2. Adjust the color svg icon stroke-width to equal 2 so that the border color is clearer

[zxuanhong]

@smbea
I added the configuration default fill color and default stroke color. This scheme is consistent with bpmn js.The configuration of bpmn js is as follows

[smbea]

Adjust the color svg icon stroke-width to equal 2 so that the border color is clearer

I'm not sure we want to change the stroke. We've had some discussions on the UI of the color picker but I don't remember if this was an issue that was discussed @nikku

[nikku]

@zxuanhong Could you tell us why we don't simply set this to the default fill and stroke color provided by bpmn-js? Why would we want to set this extra?

[zxuanhong]

@nikku In Dark mode, the color without fill or stroke should follow bpmn js in Dark mode.Or this will result in a color mismatch with bpmn js(bpmn js changes the default color situation).That is, bpmn js does the following

This causes the element color to differ from the corresponding setting

[nikku]

Exactly. This is why I'm asking:

• Why make it possible to configure an extra color, when alternatively we can read the default color configured with bpmn-js and use that?

[zxuanhong]

@nikku I haven't tried to read it, but the idea is perfect. I'll update it later

[zxuanhong]

@nikku Have changed

[zxuanhong]

@nikku Thanks again for your guidance

[nikku]

Great stuff @zxuanhong. Feels like the right approach.

[nikku]

Released with v0.6.0.