[ja] Add short causative form

[khaitruong922]

https://gohoneko.neocities.org/grammar/taekim#149%20Causative%20Verbs
https://www.tofugu.com/japanese-grammar/verb-causative-form-saseru/

The only problem is that this rule is currently polluting させられる form with 2 possible conjugations. The shortened causative form is never combined with the second way. Is there any way to handle this exception? If not then let's consider if it's worth to add this form.

[codspeed-hq]

CodSpeed Performance Report

Merging #1366 will not alter performance

_{Comparing khaitruong922:shortened-causative-form (92db6c1) with master (8509bcb)}

Summary

✅ 3 untouched benchmarks

🆕 2 new benchmarks
⁉️ 2 (👁 2) dropped benchmarks

Benchmarks breakdown

	Benchmark	master	khaitruong922:shortened-causative-form	Change
👁	japanese transformations (n=61)	16.1 ms	N/A	N/A
🆕	japanese transformations (n=63)	N/A	15.5 ms	N/A
👁	japanese transformations-full (n=166)	36.2 ms	N/A	N/A
🆕	japanese transformations-full (n=172)	N/A	38.7 ms	N/A

[khaitruong922]

Ready for review.

Added v5s for short causative form, which can conjugates to all v5 forms (including -masu), excluding potential form.

食べさせられる will only resolves to causative >> potential or passive, not short causative >> potential >> potential or passive anymore.