changed column_renamings, required_columns and column_filters to field_renamings, required_fields and field_filters respectively

Signed-off-by: Srthkdb <srthkdb@iitk.ac.in>

Author: srthkdb

tests/testdata/test_cmd/help/about_transform_config_help.txt

@@ -5,33 +5,33 @@ format, using the same format as an .ABOUT file.
 
 The attributes that can be set in a configuration file are:
 
-* column_renamings:
+* field_renamings:
 An optional map of source CSV column name to target CSV new column name that
 is used to rename CSV columns.
 
 For instance with this configuration the columns "Directory/Location" will be
 renamed to "about_resource" and "foo" to "bar":
-    column_renamings:
+    field_renamings:
         'Directory/Location' : about_resource
         foo : bar
 
 The renaming is always applied first before other transforms and checks. All
 other column names referenced below are these that exist AFTER the renamings
 have been applied to the existing column names.
 
-* required_columns:
+* required_fields:
 An optional list of required column names that must have a value, beyond the
 standard columns names. If a source CSV does not have such a column or a row is
 missing a value for a required column, an error is reported.
 
 For instance with this configuration an error will be reported if the columns
 "name" and "version" are missing or if any row does not have a value set for
 these columns:
-    required_columns:
+    required_fields:
         - name
         - version
 
-* column_filters:
+* field_filters:
 An optional list of column names that should be kept in the transformed CSV. If
 this list is provided, all the columns from the source CSV that should be kept
 in the target CSV must be listed be even if they are standard or required
@@ -40,7 +40,7 @@ transformed target CSV.
 
 For instance with this configuration the target CSV will only contains the "name"
 and "version" columns and no other column:
-    column_filters:
+    field_filters:
         - name
         - version
 

tests/testdata/test_transform/configuration

@@ -1,10 +1,10 @@
-column_renamings:
+field_renamings:
     'Directory/Filename' : about_resource
     Component: name
-column_filters:
+field_filters:
     - about_resource
     - name
     - version
-required_columns:
+required_fields:
 	- name
 	- version

tests/testdata/test_transform/configuration_scancode

@@ -1,10 +1,10 @@
-column_renamings:
+field_renamings:
 	extension : new_extension
-column_filters:
+field_filters:
 	- name
 	- new_extension
 	- about_resource
-required_columns:
+required_fields:
 	- name