[MainUI - Sitemap Pagedesigner] Wrong type "number" for list separator in Designer

[DarkC35]

The problem

Sitemap pagedesigner widget uses wrong type number for control Separator. Therefore a correct separator for a list widget (like ,) cannot be set via the designer. It is possible to set the separator via code (see screenshot below) but the set separator will not be displayed in the designer (and a following change+save of the separator with a string/text in the designer results in an unset of the seperator in the sitemap code... i guess because of validation?).

Expected behavior

Control separator should have type text so it is possible to set the separator with the designer too.

Steps to reproduce

1. make a sitemap (Settings -> Pages -> Create Sitemap)
2. add a list widget
3. try to set separator , in designer
4. save the sitemap (no error occures and separator is still visible in designer)
   
5. switch to tab Code
6. no separator prop was added in sitemap code
   
7. switch back to tab Design
8. separator , disappeared
   

Your environment

runtimeInfo:
  version: 3.1.0
  buildString: "Build #2211"
locale: de-AT
systemInfo:
  configFolder: c:\openhab\conf
  userdataFolder: c:\openhab\userdata
  logFolder: c:\openhab\userdata\logs
  javaVersion: 11.0.6
  javaVendor: Oracle Corporation
  javaVendorVersion: "18.9"
  osName: Windows 10
clientInfo:
  device:
    firefox: true
    os: windows

Additional information

The problem seems to be in this line:

openhab-webui/bundles/org.openhab.ui/web/src/components/pagedesigner/sitemap/widget-details.vue

Line 30 in eb7596c

<f7-list-input v-if="supports('separator')" label="Separator" type="number" :value="widget.config.separator" @input="updateParameter('separator', $event)" clear-button />

ListRenderer in BasicUI uses getSeparator() to split the string

openhab-webui/bundles/org.openhab.ui.basic/src/main/java/org/openhab/ui/basic/internal/render/ListRenderer.java

Line 64 in eb7596c

for (String row : state.toString().split(((List) w).getSeparator())) {

and according to openhab-core separator is of type string:

https://github.com/openhab/openhab-core/blob/4a79e9bfe7dca9f6abd1e40d3eb398a9aa2c8988/bundles/org.openhab.core.model.sitemap/src/org/openhab/core/model/sitemap/Sitemap.xtext#L104

I'm willing to submit a PR that fixes the wrong type in the widget-details.vue file.