feat(api) adds templating to the csv formated out using go's text/template

[eblechschmidt]

Implements feature proposed in #22:

• Adds default templates for all commands
• Adds template flag to specify file name for templating csv output
• Adds missing csv format to document command
• Bumps all version of go.mod file to the newes version

[eblechschmidt]

This is my first ever contribution/pull request so please help me if I missed something.

[jsattler]

@eblechschmidt thanks for your contribution! I will review your contribution within the next days and provide feedback ☺️

[jsattler]

Thanks again for your contribution! Overall it looks good 👍🏽 my only remark/concern is the tpl package and the *.tmpl files inside. Instead of having each template inside a separate file I propose that we provide the template directly as a default inside corresponding cmd/*.go file like: tmpl, err := template.New("test").Parse("{{.Count}} example template that is currently inside tpl package {{.Example}}"). What do you think?

[jsattler]

It seems like that this function is not used or do I miss something? In the past the length of the holderName could be quite long, that's why I limited it to 30 chars.