Convert to universal plugin with multiple inner plugins

[jsvd]

Currently mutate filter performs multiple mutations:

filter {
  mutate {
    rename => { .. }
    convert => { .. }
    gsub => { .. }
  }
}

However the user defined order doesn't correspond to the execution order as that is hard coded.

Using an universal plugin, we could provide each mutation as a top level filter:

filter {
  rename => { .. }
  convert => { .. }
  gsub => { .. }
}