Pointer move

[pelord]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines:https://github.com/infra-geo-ouverte/igo2/blob/master/.github/CONTRIBUTING.md#git-commit-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What is the current behavior? (You can also link to an open issue here)

What is the new behavior?
There is 3 new features included

1- Retrieve the mouse coord on move(directive = igoPointerPosition)
2- Retrieve the mouse coord on move/click combined with a key down (directive = igoPointerPositionByKey), by default, CTRL is the defined key to press down.
3- The pointer position. The pointer position return also the reverse search sources summary. If there is multiple results from the same type, only the closest will be kept. To enable for each source the pointer summary, the search source must specify this property (showInPointerSummary).

      coordinatesreverse: {
        showInPointerSummary: true
      },

Examples:
1- mouse coord = igo2-lib demo , simple map section
2- mouse coord on move/click combined with a key down = igo2-lib demo , search section. The CTRL + mouse move trigger the coord reverse search.
3- The pointer position = igo2-lib demo , search section. Use F2 to enable/disable the pointer.

Does this PR introduce a breaking change? (check one with "x")

[ ] Yes
[x] No