add support for .renderignore

[pawelprazak]

add and .ignore functionality, just like: .gitignore, .helmignore, .dockerignore, etc ...

See:

• https://golang.org/pkg/path/filepath/#Match
• https://golang.org/pkg/path/filepath/#Glob
• .helmignore ".*" entry incorectly ignores current directory helm/helm#1776
• path/filepath: Glob should support ** for zero or more directories golang/go#11862

[github-actions]

Marked as stale due to inactivity. Will be closed in 30 days.

[github-actions]

Closed due to inactivity for 90 days.