Deprecate vim.diagnostic.goto_prev() and vim.diagnostic.goto_next() in
favor of a unified vim.diagnostic.jump() interface.
We cannot name the function "goto()" because some of our tooling
(luacheck and stylua) fail to parse it, presumably because "goto" is a
keyword in newer versions of Lua.
vim.diagnostic.jump() also allows moving to a specific diagnostic and
moving by multiple diagnostics at a time (useful for creating mappings
that use v:count).
8ba73f0e4c