Upgrade to v0.12.x, remove nvim-treesitter

Switch to tree-sitter-manager.nvim for managing tree-sitter parsers and
queries. Also fixes upgrade issues.

plugin/mappings.lua

@@ -59,7 +59,7 @@ vim.keymap.set('n', '<leader>gw', function()
 end, { desc = 'Format whole file with gw' })
 
 vim.keymap.set('n', '<leader>fm', function()
-  if vim.o.foldexpr == 'nvim_treesitter#foldexpr()' then
-    vim.opt.foldexpr = 'nvim_treesitter#foldexpr()'
+  if vim.o.foldexpr == 'v:lua.vim.treesitter.foldexpr()' then
+    vim.opt.foldexpr = 'v:lua.vim.treesitter.foldexpr()'
   end
 end)

plugin/settings.lua

@@ -89,7 +89,7 @@ vim.opt.joinspaces = false
 -- Set fold level to something high
 vim.opt.foldlevel = 20
 vim.opt.foldmethod = 'expr'
-vim.opt.foldexpr = 'nvim_treesitter#foldexpr()'
+vim.opt.foldexpr = 'v:lua.vim.treesitter.foldexpr()'
 vim.opt.foldtext = ''
 vim.opt.fillchars = { fold = ' ' }
 

plugin/ui.lua

@@ -1,17 +1,3 @@
--- Customise LSP UI
-vim.lsp.handlers['textDocument/hover'] = vim.lsp.with(
-  vim.lsp.handlers.hover, {
-    border = 'rounded',
-    title = 'Hover',
-  }
-)
-vim.lsp.handlers['textDocument/signatureHelp'] = vim.lsp.with(
-  vim.lsp.handlers.signature_help, {
-    border = 'rounded',
-    title = 'Signature Help',
-  }
-)
-
 -- Customise diagnostic UI
 vim.diagnostic.config({
   float = {