Add datetime parser

[GreatYYX]

Add datetime parser

[bhatiadivij]

I integrated the etk.wikidata.utils.parse_datetime_string function but it turns out that it doesn't work on some data files.

Debugging Steps Performed:

1. Debugged the variables being passed in realtime.
2. I tried interchanging data file formats but it didn't help.

To reproduce the same issue perform the following steps:

1. Checkout branch feature/datetime_parser
2. Run T2WML server and visit http://localhost:5000
3. Try downloading the .ttl using the files attached.
4. The error occurs here:

   t2wml/Code/handler.py

   Line 297 in 433a4d8

   datetime_string, precision = parse_datetime_string(temp_dict["value"], additional_formats=[temp_dict["format"]])

   
   Files.zip

[szeke]

The YAML file should be:

statementMapping:
  region:
    - left: D
      right: BJ
      top: 5
      bottom: 270
  template:
    item: item(A/$row)
    property: item(D/$row)
    value: value($col/$row)
    # unit: item(H/$row)
    qualifier:
      - property: P585
        value: value($col/5)
        format: "%Y"
        calendar: Q1985727
        precision: year
        time_zone: 0
      - property: P248 # stated in
        value: Q21540096 # World Bank database
      - property: P275 # license
        value: Q20007257 # Creative Commons Attribution 4.0 International

After adding the format attribute the TTL generation works fine.

However, if there is no format keyword, it fails silently, no output and no error message.