feat(html/formatter): self close tag add slash char

[suxin2017]

Summary

fix: #3975

Test Plan

add snap test

[codspeed-hq]

CodSpeed Performance Report

Merging #3984 will degrade performances by 7.08%

_{Comparing suxin2017:feat_self_close_tag_add_slash (096f909) with main (33d0958)}

Summary

❌ 1 regressions
✅ 106 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	suxin2017:feat_self_close_tag_add_slash	Change
❌	dojo_11880045762646467684.js[cached]	7.9 ms	8.5 ms	-7.08%

[suxin2017]

@dyc3 How do I trigger the html snapshot test? I modify the snapshot file but the test file is missing updates

[dyc3]

The snapshot tests are currently broken, see #3979

[dyc3]

I've merged #3979, go ahead and rebase this.