feat: add start and end positions of tag nodes (#246)

Closes #134

* feat: Add start and end positions of tag nodes

Improves accuracy of row/col error reporting. Now targets the start of the relevant token instead of the end.

* Simplify language for TagNode and Token

* Update static TagNode.create to ingest setStart() logic

improve readability of end pos offset for no attr tags

packages/bbob-parser/src/parse.ts

@@ -185,7 +185,7 @@ function parse(input: string, opts: ParseOptions = {}) {
   function handleTagStart(token: Token) {
     flushTagNodes();
 
-    const tagNode = TagNode.create(token.getValue(), {}, []);
+    const tagNode = TagNode.create(token.getValue(), {}, [], { from: token.getStart(), to: token.getEnd() });
     const isNested = isTokenNested(token);
 
     tagNodes.push(tagNode);
@@ -203,6 +203,10 @@ function parse(input: string, opts: ParseOptions = {}) {
    * @param {Token} token
    */
   function handleTagEnd(token: Token) {
+    const lastTagNode = nestedNodes.last();
+    if (isTagNode(lastTagNode)) {
+      lastTagNode.setEnd({ from: token.getStart(), to: token.getEnd() });
+    }
     flushTagNodes();
 
     const lastNestedNode = nestedNodes.flush();