Farewell to Bram and dedicate upcoming Vim 9.1 to him (vim/vim#12749)

https://github.com/vim/vim/commit/e978b4534a5e10471108259118c0ef791106fd92



Also update the header for the following files that were converted to Vim9
script upstream:

- autoload/ccomplete.lua (vim9jitted)
- ftplugin.vim
- ftplugof.vim
- indent.vim
- indent/vim.vim
- makemenu.vim

This also updates the "Last Change" dates, even if some changes (due to rewrites
to Vim9 script) were not ported.

There's still a few other places where Bram is still mentioned as a maintainer
in the files we and Vim have:

- ftplugin/bash.vim
- indent/bash.vim
- indent/html.vim
- indent/mail.vim
- macros/accents.vim
- macros/editexisting.vim
- syntax/bash.vim
- syntax/shared/typescriptcommon.vim
- syntax/tar.vim
- syntax/typescript.vim
- syntax/typescriptreact.vim
- syntax/zimbu.vim

Maybe future patches will address that.

Also exclude changes to .po files that didn't apply automatically (the
`:messages` maintainer string isn't used in Nvim anyway).

Co-authored-by: Christian Brabandt <cb@256bit.org>