Add replacment formatter

Author: manuelbrack

Diff for: src/datatrove/pipeline/formatters/__init__.py

@@ -1,3 +1,4 @@
 from .ftfy import FTFYFormatter
 from .pii import PIIFormatter
 from .symbol_lines_remover import SymbolLinesFormatter
+from custom import CustomFormatter

Diff for: src/datatrove/pipeline/formatters/custom.py

@@ -0,0 +1,13 @@
+from .base import BaseFormatter
+
+
+class CustomFormatter(BaseFormatter):
+    def __init__(self, replacements: list):
+        super().__init__()
+        self.replacements = replacements
+
+    def format(self, text: str) -> str:
+        for replacement in self.replacements:
+            text = text.replace(replacement[0], replacement[1])
+
+        return text