Add function and filter to convert string to date

[liamrharwood]

We currently have the strtotime function and filter that can be used to convert a string object into a DateTime object. However, we don't have a good way to do this for Date objects that don't include a time.

For instance, there's no good way to convert the string 3/4/21 to a different format, since it doesn't include the time.

This PR adds the new strtodate function/filter that can convert dates without time.

For instance, you can do something like this:

{{ "3/4/21"|strtodate('d/M/yy')|datetimeformat('%B %e, %Y') }}

To output the following:
March 4, 2021

[boulter]

Should we call it strptime? That seems like the closest equivalent in python and what someone would use in Jinja.

https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior

[liamrharwood]

I'm not against it, but we already have strtotime so I thought strtodate would be consistent.

[mattcoley]

Why did we name it strtotime in the first place?

[mattcoley]

#258 👎

[mattcoley]

We could write the object to String here