enh(ui): Add label widget attribute

[quborg]

Description

Make "label" attribute available when editing gauge widget.

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software

Target serie

• dev

How this pull request can be tested ?

• Create new map
• Create Gauge widget
• Enter a label
• Save map
• Edit Gauge (display label: checked, Use resource name: unchecked)
• Submit Edit Gauge Modal
• Should find label filled above

Checklist

Community contributors & Centreon team

• I have followed the coding style guidelines provided by Centreon
• I have commented my code, especially new classes, functions or any legacy code modified. (docblock)
• I have commented my code, especially hard-to-understand areas of the PR.
• I have rebased my development branch on the base branch (master, maintenance).