attribute table - display tooltip on field name hover

[Gaetanbrl]

Description

In addition of #637, some user needs more information about a field (e.g if metadata not exists). We propose an enhancement to display a short text when a user hover attribute field header value.

Thi contribution will allow to use use a new tooltip property like :

{
  "name": "FeatureEditor",
  "cfg": {
    "maxZoom": 21,
    "customEditorsOptions": {
      "rules": [
        {
          "regex": {
            "attribute": "s_r0.6",
            "url": "regex to match a specific url",
            "typeName": "layerName"
          },
          "tooltip": "Scnerio - 60%"
        }
      ]
    }
  }

What kind of improvement you want to add? (check one with "x", remove the others)

• Minor changes to existing features
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Mapstore2georchestra improvement
• Mapstore2 improvement
• Other... Please describe:

Other useful information