(core) move data engine code to core

Summary:
this moves sandbox/grist to core, and adds a requirements.txt
file for reconstructing the content of sandbox/thirdparty.

Test Plan:
existing tests pass.
Tested core functionality manually.  Tested docker build manually.

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2563

sandbox/grist/functions/lookup.py

@@ -0,0 +1,80 @@
+# pylint: disable=redefined-builtin, line-too-long
+
+def ADDRESS(row, column, absolute_relative_mode, use_a1_notation, sheet):
+  """Returns a cell reference as a string."""
+  raise NotImplementedError()
+
+def CHOOSE(index, choice1, choice2):
+  """Returns an element from a list of choices based on index."""
+  raise NotImplementedError()
+
+def COLUMN(cell_reference=None):
+  """Returns the column number of a specified cell, with `A=1`."""
+  raise NotImplementedError()
+
+def COLUMNS(range):
+  """Returns the number of columns in a specified array or range."""
+  raise NotImplementedError()
+
+def GETPIVOTDATA(value_name, any_pivot_table_cell, original_column_1, pivot_item_1=None, *args):
+  """Extracts an aggregated value from a pivot table that corresponds to the specified row and column headings."""
+  raise NotImplementedError()
+
+def HLOOKUP(search_key, range, index, is_sorted):
+  """Horizontal lookup. Searches across the first row of a range for a key and returns the value of a specified cell in the column found."""
+  raise NotImplementedError()
+
+def HYPERLINK(url, link_label):
+  """Creates a hyperlink inside a cell."""
+  raise NotImplementedError()
+
+def INDEX(reference, row, column):
+  """Returns the content of a cell, specified by row and column offset."""
+  raise NotImplementedError()
+
+def INDIRECT(cell_reference_as_string):
+  """Returns a cell reference specified by a string."""
+  raise NotImplementedError()
+
+def LOOKUP(search_key, search_range_or_search_result_array, result_range=None):
+  """Looks through a row or column for a key and returns the value of the cell in a result range located in the same position as the search row or column."""
+  raise NotImplementedError()
+
+def MATCH(search_key, range, search_type):
+  """Returns the relative position of an item in a range that matches a specified value."""
+  raise NotImplementedError()
+
+def OFFSET(cell_reference, offset_rows, offset_columns, height, width):
+  """Returns a range reference shifted a specified number of rows and columns from a starting cell reference."""
+  raise NotImplementedError()
+
+def ROW(cell_reference):
+  """Returns the row number of a specified cell."""
+  raise NotImplementedError()
+
+def ROWS(range):
+  """Returns the number of rows in a specified array or range."""
+  raise NotImplementedError()
+
+def VLOOKUP(table, **field_value_pairs):
+  """
+  Vertical lookup. Searches the given table for a record matching the given `field=value`
+  arguments. If multiple records match, returns one of them. If none match, returns the special
+  empty record.
+
+  The returned object is a record whose fields are available using `.field` syntax. For example,
+  `VLOOKUP(Employees, EmployeeID=$EmpID).Salary`.
+
+  Note that `VLOOKUP` isn't commonly needed in Grist, since [Reference columns](col-refs) are the
+  best way to link data between tables, and allow simple efficient usage such as `$Person.Age`.
+
+  `VLOOKUP` is exactly quivalent to `table.lookupOne(**field_value_pairs)`. See
+  [lookupOne](#lookupone).
+
+  For example:
+  ```
+  VLOOKUP(People, First_Name="Lewis", Last_Name="Carroll")
+  VLOOKUP(People, First_Name="Lewis", Last_Name="Carroll").Age
+  ```
+  """
+  return table.lookupOne(**field_value_pairs)