Big structure changes (check commit description)

- Moved most of the parser functions/files to the core package.
- Converted tools file to a package and made separate files for similar functions.
- Now all fetcher engines return a Response object
- Instead of selecting an engine to use and passing config to it, we have separate fetcher classes so the user can choose what to use while importing.
- I added a new custom fetcher so the user can create and use an engine.
- More...

scrapling/core/mixins.py

@@ -0,0 +1,74 @@
+
+class SelectorsGeneration:
+    """Selectors generation functions
+    Trying to generate selectors like Firefox or maybe cleaner ones!? Ehm
+    Inspiration: https://searchfox.org/mozilla-central/source/devtools/shared/inspector/css-logic.js#591"""
+
+    def __general_selection(self, selection: str = 'css') -> str:
+        """Generate a selector for the current element.
+        :return: A string of the generated selector.
+        """
+        selectorPath = []
+        target = self
+        css = selection.lower() == 'css'
+        while target is not None:
+            if target.parent:
+                if target.attrib.get('id'):
+                    # id is enough
+                    part = (
+                        f'#{target.attrib["id"]}' if css
+                        else f"[@id='{target.attrib['id']}']"
+                    )
+                    selectorPath.append(part)
+                    return (
+                        " > ".join(reversed(selectorPath)) if css
+                        else '//*' + "/".join(reversed(selectorPath))
+                    )
+                else:
+                    part = f'{target.tag}'
+                    # We won't use classes anymore because I some websites share exact classes between elements
+                    # classes = target.attrib.get('class', '').split()
+                    # if classes and css:
+                    #     part += f".{'.'.join(classes)}"
+                    # else:
+                    counter = {}
+                    for child in target.parent.children:
+                        counter.setdefault(child.tag, 0)
+                        counter[child.tag] += 1
+                        if child._root == target._root:
+                            break
+
+                    if counter[target.tag] > 1:
+                        part += (
+                            f":nth-of-type({counter[target.tag]})" if css
+                            else f"[{counter[target.tag]}]"
+                        )
+
+                selectorPath.append(part)
+                target = target.parent
+                if target is None or target.tag == 'html':
+                    return (
+                        " > ".join(reversed(selectorPath)) if css
+                        else '//' + "/".join(reversed(selectorPath))
+                    )
+            else:
+                break
+
+        return (
+            " > ".join(reversed(selectorPath)) if css
+            else '//' + "/".join(reversed(selectorPath))
+        )
+
+    @property
+    def css_selector(self) -> str:
+        """Generate a CSS selector for the current element
+        :return: A string of the generated selector.
+        """
+        return self.__general_selection()
+
+    @property
+    def xpath_selector(self) -> str:
+        """Generate a XPath selector for the current element
+        :return: A string of the generated selector.
+        """
+        return self.__general_selection('xpath')