feat(javadoc): add parser and queries

Previously java was configured to use doxygen parser for documentation
comments, but javadocs are not doxygen. Inline tags have a different
syntax, block tags are not recognized, and doxygen creates a lot of
errors during highlighting.

Add parser for javadoc comments, with queries for highlights and
injections.

lua/nvim-treesitter/parsers.lua

@@ -1127,6 +1127,14 @@ list.java = {
   maintainers = { "@p00f" },
 }
 
+list.javadoc = {
+  install_info = {
+    url = "https://github.com/rmuir/tree-sitter-javadoc",
+    files = { "src/parser.c", "src/scanner.c" },
+  },
+  maintainers = { "@rmuir" },
+}
+
 list.javascript = {
   install_info = {
     url = "https://github.com/tree-sitter/tree-sitter-javascript",