feat: allow to be lazy loaded on InsertEnter

[lopi-py]

No description provided.

[PriceHiller]

Hello, thanks for the PR!

I'm assuming there's a performance problem that prompted this PR? To my knowledge nvim-ts-autotag is pretty quick on load, there really shouldn't be much of a startup impact at all (around ~5 ms).

If you can demonstrate a significant startup performance hit, I'm open to merging this (assuming lazy loading on InsertEnter works, of course).

[lopi-py]

I lazy/defer load nvim-treesitter because the typescript parser is slow (not shown in the startup time but the delay is very noticeable) when I open a buffer, but nvim-ts-autotag forces nvim-treesitter to load

I definitely tested this before opening a PR.

[PriceHiller]

Ah, that makes sense. Thanks again for the PR!