I needed "split" specifically so I can do something like:
```hcl
variable PLATFORMS {
default = "linux/amd64"
}
target foo {
platforms = split(",", "${PLATFORMS}")
# other stuff
}
```
Where the existing "csvdecode" does not work for this because it parses
the string into a list of objects instead of a list of strings.
I went ahead and just added all the available new functions.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Brian Goff