Merge layer_view extension

[VenissaCarolQuadros]

PR description

Created a new extension called 'layer_view' extension in the TopPanel, which can easily make only the current layer visible. I find myself repeatedly doing but have to do this except it earlier required clicking the eye icon on each of the layers which gets tedious if there are many layers.

It has been designed as follows:

1. When turned on the 'layerinvis' is included in the class list of all but the current layer
2. The tool can be disabled either by clicking on the tool again or clicking on one of the 'eye' icons on the side. The latter is done to not disrupt the functionality of the LayerPanel.

I realize this is not a requested feature but thought it would be a neat feature to add. The default state in the ConfigObj.js is set to false but could be set to true id required.

Checklist

Note that we require UI tests to ensure that the added feature will not be
nixed by some future fix and that there is at least some test-as-documentation
to indicate how the fix or enhancement is expected to behave.

• - Added Cypress UI tests
• - Ran npm test, ensuring linting passes and that Cypress UI tests keep
  coverage to at least the same percent (reflected in the coverage badge
  that should be updated after the tests run)
• - Added any user documentation. Though not required, this can be a big
  help both for future users and for the PR reviewer.

[jfhenon]

The button is not styled like others (white/orange). Could you fix this? The rest is good and thank you for the addition.