ddev script for developer docs

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Description:

Adds a script to setup a local install with ddev

Review

• [x] Functional review done
• [x] Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• [x] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• [x] Security review done
• [x] Wording review done
• [ ] Code review done
• [x] Tests were added if useful/possible
• [x] Reviewed for breaking changes
• [x] Developer changelog updated if needed
• [x] Documentation added if needed
• [x] Existing documentation updated if needed