Melon and pumpkin stem model template names are badly named

The melon stem and pumpkin stem blocks, as well as their attached variants, both reference template models for most of their definition. However, their templates' names have rather unexpected names.

The templates are named as follows:

• stem_growth0.json
• stem_growth1.json
• stem_growth2.json
• stem_growth3.json
• stem_growth4.json
• stem_growth5.json
• stem_growth6.json
• stem_growth7.json
• stem_fruit.json

The models themselves, however, are named like this:

• [FRUIT NAME]_stem_stage0.json
• [FRUIT NAME]_stem_stage1.json
• [FRUIT NAME]_stem_stage2.json
• [FRUIT NAME]_stem_stage3.json
• [FRUIT NAME]_stem_stage4.json
• [FRUIT NAME]_stem_stage5.json
• [FRUIT NAME]_stem_stage6.json
• [FRUIT NAME]_stem_stage7.json
• attached_[FRUIT NAME]_stem.json

Not only are the template models named very inconsistently from the actual models that reference them, they also lack the leading "template_" like a large number of other template model files do. This should probably be fixed by changing the models to something like "template_stem_stage[NUMBER].json" and "template_attached_stem.json", as the current naming system is very confusing for resource pack makers.

I'm not entirely sure about this, but stem_growth7.json may be completely redundant as well, due to the existence of tinted_cross.json (any potential visual differences from other stems is almost certaintly due to MC-96463).