Better `range` support for `go template`

[akranga]

As a user I want to define a parameter and then iterate over its values in the go template. Today we can define parameter value as a string. Then go-template needs to support split function so it would produce list out of string

• add split function to gotemplate
• add compact function to gotemplate
• add join function to gotemplate
• add first function to gotemplate
• add formatSubdomain to gotemplate
• add unit test
• update documentation

[arkadijs]

IIRC, templating engine supports Sprig functions.

[akranga]

@arkadijs thanks! I was thinking about Sprig there are lot functions... not sure if all needed for go templates and not sure if we can test all of them... Also from usability perspective, functions might be confusing for the user. For example it maybe hard for user to distinguish with which type do they operate etc... So, variable arguments and good type guessing might be more friendlier nature...

• we can always fallback to sprig indeed!

[arkadijs]

It's already in the Hub:
https://github.com/epam/hubctl/blob/master/go.mod#L11

[akranga]

It looks like everything except formatSubdomain can be removed now