Sanitize cluster and worker pool names

[rata]

Cluster and worker pool names are used in terraform templates. For example, here and here, but there are some more usages.

Also, lokomotive executes terraform using -target=<user-generated-string> and this can easily lead in the future to arbitrary code execution (in the user local computer, so not so heavy) if the user uses something like worker; sudo rm -rf / as worker pool name. Examples are here

The terraform executor, though, is doing it's job correctly and those simple code executions are not possible today (it's not using a shell, etc.). However, it seems reasonable to sanitize all user input, specially if we are using it to construct command to run later (like terrafor apply -target <user-input>).

In AWS it seems we are just using it in terraform templates, not to construct a terraform command, so it seems safer (there would need to be a bug in terraform itself for it to be exploitable). But the general concern to sanitize user input, specially when using it to run commands, seems reasonable to have in a common layer for all providers.