Make node.js example

[Alexey Palazhchenko]

Let's finish it after #866.

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Let's update https://github.com/FerretDB/nodejs-example to do the same as our other examples:

• add dependabot config;
• do our usual testing script;
• accept MongoDB URI as an argument;
• enforce Strict API via flag.
• remove everything else.

Then add it into dance.