update HTML output and review UI for vector properties

[Gustry]

Description

• lineEdit which are read only have a gray background. It was confusing to have a white background.
• new tab information to display the HTML output. We need to review these sections. I have more or less try to replicate : http://188.165.62.190/layers/geonode:italy/metadata_detail
• the previous General tab has been split into 2 tabs:
  • Metadata : for editing layer name and metadata
  • Source : for editing CRS, extent, SQL filter

I will not merge PR here. I easier to review work in a PR. Then I will make a PR to QGIS. Editing metadata is not in this PR.

Note for QGIS : In QT5, to concatenate strings (HTML), it's better to use QStringBuilder, but I'm not sure QGIS enabled this feature since we use qt5.

[timlinux]

Ah that is a good approach @Gustry +1 from me to try to get this upstream as a first step merge, and then improve on it as we go.

[Gustry]

This has been merged in QGIS core