Replace vim.opt with vim.o

[oriori1703]

Even though this change is not mandatory until all of the plugins use the new vim.o interface, as discussed in #1264 , I think there it is still beneficial switching to vim.o.

In contrast to vim.opt, vim.o opens the documentation on hover, and provides type hints which will be useful for beginners (and also experts who are just lazy ;).

In addition it is more intuitive to get the value of the option (e.g. vim.bo.modifiable instead of vim.opt_local.modifiable:get()).

The main downside is that it is less convenient in the cases where vim.opt provides a table (This is tracked in neovim/neovim#20107).
So for now I left vim.opt.listchars and vim.opt.rtp unchanged.

[brianhuster]

I think there should be document about the difference between them, and why you use vim.o for this but keep vim.opt for that

[oriori1703]

I think there should be document about the difference between them, and why you use vim.o for this but keep vim.opt for that

I added a comment explaining why I choose to use vim.opt and referencing the manual for an explanation about the difference.
What do you think?

[brianhuster]

LGTM