We now generate the read operation which sets the various encodings of
the random value such that adding new ones does not require generating a
new random value.
We also verify that these are set correctly via the acceptance tests.
This commit makes three related changes to the `random_id` resource:
1. Deprecate the `b64` attribute
2. Introduce a new `b64_url` attribute which functions in the same
manner as the original `b64` attribute
3. Introduce a new `b64_std` attribute which uses standard base64
encoding for the value rather than URL encoding.
Resource identifiers continue to use URL encoded base 64.
The reason for adding standard encoding of the base 64 value is to allow
the use of generated values as a Serf Encryption Key for separating
Consul clusters - these rely on standard encoding and do not permit some
characters which are allowed by URL encoding. `b64_url` is introduced
in order that there is consistency in specifying the desired encoding
during interpolation.
This resource generates a cryptographically-strong set of bytes and
provides them as base64, hexadecimal and decimal string representations.
It is intended to be used for generating unique ids for resources
elsewhere in the configuration, and thus the "keepers" would be set to
any ForceNew attributes of the target resources, so that a new id is
generated each time a new resource is generated.