Feature/add panama holidays

[amitsamtani]

This Pull Request introduces support for the Panamanian holidays.

This is a duplicate pull request for the country Panama. Original PR.

This version of the PR adds support for:

• Carnival Holidays
• Bridge Days (also known as "puentes") in Panama. If a holiday falls on a Sunday, they give the following Monday off

[Nielsvanpach]

Thanks! Did you verify the results generated in the snapshot file?

[amitsamtani]

Hi Niels, yes. I reviewed the results in the generated snapshot file and the holidays appear in order along with the bridged holidays we have in our country.

[Nielsvanpach]

Thanks! PR looks good, I'll wait on some approvals by others before merging.