Remove legacy (old API) mysql_password function

[alexjfisher]

There's been a properly namespaced modern mysql::password function for
some time. See #1044

When the modern API non-namespaced shim was removed in a68004c
the puppet/parser/functions version still existed so users who hadn't
migrated to mysql::password would have reverted to this legacy API version.

This commit finally removes the legacy version, but puts back the shim
for now (to not create a breaking change just yet).

Both namespaced and non-namespaced shim are tested.

[oniGino]

running module 10.7.0 getting function not found on mysql::password, with puppet 5.5.20

[sazzle2611]

running module 10.8.0 with puppet 5.5.22 and getting error Unknown function: 'mysql::password'

[Jimadine]

@sazzle2611 @oniGino Either of you work out what was going on with puppet 5.5..2x and the mysql::password function? I am facing the same Error: Evaluation Error: Unknown function: 'mysql::password'. issue. (puppet 5.5.22 on ubuntu 18)

[sazzle2611]

@Jimadine sorry no I didn't, our issue was resolved in the end, probably after an upgrade but can't remember for sure now

[alexjfisher]

@Jimadine My guess is that you're calling the function from a module which doesn't list puppetlabs/mysql as a dependency in its metadata.json?

From https://github.com/puppetlabs/puppet-specifications/blob/master/language/func-api.md ...

Note: A module that wants to call a function in another module must either have that module listed as a dependency, or have no dependencies entry at all in its metadata.json. This requirement is enforced at runtime to help users keep metadata for modules up to date as users then simply need to install a module and its dependencies. If a module does not have the correct dependencies listed the runtime will simply not find the function.

This restriction was removed in Puppet 6.0.0. (It was almost removed in 5.5.x too, but the change reverted due to a regression.)

[Jimadine]

@alexjfisher Thank you! That was indeed the cause of the problem.