Be able to use files from https endpoints

[JimPaine]

Description

For common files such as browser user agents it would be great to have a shared file which can be read over http

Example

$ lignator -t 'User agents: ${linefromfile(https://raw.githubusercontent.com/microsoft/lignator/samples/useragents.txt)}'

Considerations

• Token name might not be appropriate
• New token or change existing
• Should templates also be updated work over http (could be good for standard templates like nginx)
• Outputs?