Add feature: previous tree and next tree button

[dadiorchen]

Actually, the function of this feature has been finished in the https://github.com/Greenstand/treetracker-web-map-client/tree/master also you can find it in the website online : map.treetracker.org

The goal of this issue is to:

• Migrate this feature to the core
• Temporarily add two button (as shown in the picture) and add the logic of clicking these two buttons.
• We will open a new issue when our designer has finished the design of the buttons, and replace the UI with new design.

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Some hints:

• Please read our readme for more information/guide/tutorial.
• Here is an engineering book in Greenstand.
• To know more about our organization, visit our website.
• If you want to join the slack community (some resources need the community member's permission), please leave your email address.