Add h3 worldmap demo

[rudifa]

This PR replaces the PR#25.

@olange please review and test.

It implements all (I think) of improvements discussed in the 'revise' comment series under PR25.

This branch is rebased on today's main c937564 (upstream/main, origin/main, origin/HEAD, main)(2022-05-02 11:13:20 +0200)(GitHub).

h3-worldmap % git lg 5                                                                                                    [add-h3-worldmap-demo-3 L|✔]
* 1ee0dae (HEAD -> add-h3-worldmap-demo-3)(2022-05-02 13:45:34 +0200)(Rudi Farkas)h3-worldmap-projection-select: rename event to update-selected, simpify event dispatch; move in the import AVAILABLE_PROJECTIONS and its use from h3-worldmap-demo
* 769c9f7(2022-05-02 13:45:34 +0200)(Rudi Farkas)move  src/demo/h3-worldmap-demo.js -> dev/h3-worldmap-demo.js, src/demo/h3-worldmap-projection-select.js -> h3-worldmap-projection-select.js, update dev/index.html
* 14c9a32(2022-05-02 13:45:34 +0200)(Rudi Farkas)add <h3-worldmap-demo> <h3-worldmap-projection-select>, display in dev/index.html
* 0ed0363(2022-05-02 13:45:34 +0200)(Rudi Farkas).gitignore: add .DS_store
*   c937564 (upstream/main, origin/main, origin/HEAD, main)(2022-05-02 11:13:20 +0200)(GitHub)Adds `firstLayout()` lifecycle method and calls `_measureSVGElement()`
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[rudifa]

@olange
I'm closing this PR #29, its features have been ported to PR #25 (Monday ~ 5 pm).