Current tests can leave files around if tests fail, and even though they
use rand, it's not seeded, different runs can share the same output file
which causes other failures (e.g., file exists when it's not expected
to).  Avoid this by using  t.TempDir which automatically removed after
tests have run.

Co-authored-by: Abhinav Gupta <[email protected]>

This is a prefactor for Windows support (#621).
TestOpen currently relies on a hardcoded error "no such file or
directory" if a file is not found. However, this error message is
OS-specific.  We can now rely on `errors.Is(err, fs.ErrNotExist)`
if we wrap errors using %w instead of %v.

Co-authored-by: Abhinav Gupta <[email protected]>

Add a new function LevelOf that reports the minimum enabled log level
for a LevelEnabler.
This works by looping through all known Zap levels in-order,
returning the newly introduced UnknownLevel if none of the known levels
are enabled.
A LevelEnabler or Core implementation may implement the Level() Level
method to override and optimize this behavior.
AtomicLevel already implemented this method.
This change adds the method to all Core implementations shipped with
Zap.
Note:
UnknownLevel is set at FatalLevel+1 to account for the possibility that
users of Zap are using DebugLevel-1 as their own custom log level--even
though this isn't supported, it's preferable not to break these users.
Users are less likely to use FatalLevel+1 since Fatal means "exit the
application."
Refs #1144
Supersedes #1143, which was not backwards compatible
Refs GO-1586

We're seeing some issues get filed that are being converted to
Discussions manually. Let's add a template on question so that
we can redirect folks to Discussions page directly.

Instead of a fake issue template, show a Discussions link.

…ects (#1155)

Add a new Zap field constructor that encodes a slice of zero or more
objects which implement fmt.Stringer interface into a Zap array.

Usage:

```go
//	type Request struct{ ... }
//	func (a Request) String() string
//
//	var requests []Request = ...
//	logger.Info("sending requests", zap.Stringers("requests", requests))
```

This API uses a type parameter so that users don't have to
build a `[]fmt.Stringer` out of a `[]Request`,
and can pass the `[]Request` directly to the API.

We may need a StringerValues constructor to mirror ObjectValues in the future.

Credits: @zmanji, @abhinav for the suggestions

This release includes the following changes:
v1.22.0...23d6cc7

Refs GO-1609