fix: fixes crash when fertilizing crops

[irontofu1]

Checklist

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• I wrote the PR title in conventional commit format.
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Purpose of change

Fixes #4446. Verify by attempting to fertilize any planted crop, which would previously cause a seg fault and crash the game.

Describe the solution

I believe this was caused by the order of the code in iexamine::fertilize_plant. I'm skipping some of the steps, but the relevant ones were in this order before: get a pointer to the seed item being fertilized -> spawn fertilizer item on that tile (so it can only be fertilized once) -> use seed pointer to format a game message with the proper plant name. I think that spawning the fertilizer would invalidate the seed pointer and cause the seg fault when trying to get its name. I just changed the order so that the fertilizer is spawned before we use the iterator to get the seed pointer.

Describe alternatives you've considered

Still new to C++ so this was the only solution I could come up with. I'm more than open to others but this felt like the safest way to fix the issue without breaking something else.

Testing

Fertilized several crop types (wheat, tomatoes, beans) with both commercial and liquid fertilizer. No crash. Was still only able to fertilize each tile once.

Additional context