Add bool flag to indicate purged processed folder in visit dir (#256)

Author: KarlLevik

schemas/ispyb/updates/2025_02_14_BLSession_purgedProcessedData.sql

@@ -0,0 +1,8 @@
+INSERT IGNORE INTO SchemaStatus (scriptName, schemaStatus) VALUES ('2025_02_14_BLSession_purgedProcessedData.sql', 'ONGOING');
+
+ALTER TABLE BLSession
+  ADD purgedProcessedData boolean DEFAULT 0
+    COMMENT 'Flag to indicate whether the processed folder in the associated visit directory has been purged',
+  ALGORITHM=INSTANT;
+
+UPDATE SchemaStatus SET schemaStatus = 'DONE' WHERE scriptName = '2025_02_14_BLSession_purgedProcessedData.sql';