* passwordstore: Add configurable locking
Passwordstore cannot be accessed safely in parallel, which causes
various issues:
- When accessing the same path, multiple different secrets are
returned when the secret didn't exist (missing=create).
- When accessing the same _or different_ paths, multiple pinentry
dialogs will be spawned by gpg-agent sequentially, having to enter
the password for the same gpg key multiple times in a row.
- Due to issues in gpg dependencies, accessing gpg-agent in parallel
is not reliable, causing plays to fail (this can be fixed by adding
`auto-expand-secmem` to _~/.gnupg/gpg-agent.conf_ though).
These problems have been described in various github issues in the past,
e.g., ansible/ansible#23816 and ansible/ansible#27277.
This cannot be worked around in playbooks by users in a non-error-prone
way.
It is addressed by adding new configuration options:
- lock:
- readwrite: Lock all operations
- write: Only lock write operations (default)
- none: Disable locking
- locktimeout: Time to wait for getting a lock (s/m/h suffix)
(defaults to 15m)
These options can also be set in ansible.cfg, e.g.:
[passwordstore_lookup]
lock=readwrite
locktimeout=30s
Also, add a note about modifying gpg-agent.conf.
* Tidy up locking config
There is no reason why lock configuration should be part of self.paramvals.
Now locking and its configuration happen all in one place.
* Change timeout description wording to the suggested value.
* Rearrange plugin setup, apply PR feedback
