Configuration keys are simple namespace/name pairs, delimited by
":". For compatability, we also allow
"<namespace>:config:<name>", but we always record the "nice" name in
`Pulumi.<stack-name>.yaml`.
While `pulumi config` and friends would block setting a key like
`a🅱️c` (where the "name" has a colon in it), it would allow
`a:config:b:c`. However, this would be recorded as `a🅱️c` in
`Pulumi.<stack-name>.yaml`, which meant we'd error when parsing the
configuration file later.
To work around this, disallow ":" in the "name" part of a
configuration key. With this change the following all work:
```
keyName
my-project:keyName
my-project:config:keyName
```
However, both
`my-project:keyName:subKey`
`my-project:config:keyName:subKey`
are now disallowed.
I considered allowing colons in subkeys, but I think it adds more
confusion (due to the interaction with how we allow you elide the
project name in the default case) than is worthwhile at this point.
Fixes#2171
When serializing config.Key's we now write them as <package>:<name>
instead of <package>:config:<name>. We continue to support reading the
older format for compatability with older files.
config.Key has become a pair of namespace and name. Because the whole
world has not changed yet, there continues to be a way to convert
between a tokens.ModuleMember and config.Key, however now sometime the
conversion from tokens.ModuleMember can fail (when the module member
is not of the form `<package>:config:<name>`).
I'll be changing the structure of the representation of config.Key, so
let's write some tests first to ensure we can continue to treat
everything as JSON and YAML.
