Previously, if an exception was thrown during request handling after
the response had been committed, i.e. after the status and headers
had been written, the metrics filter would assume that it was a 500
response. This was potentially inaccurate as the status had already
been sent to the client and before the exception was thrown and it
may have been something other than a 500.

This commit updates MetricsFilter so that it will use the
status from the response if the response has been committed even when
an exception is thrown.

Closes gh-7277

Closes gh-7275

Closes gh-6996

Closes gh-7298

Closes gh-7297

Closes gh-7296

Closes gh-7295

Closes gh-7294

Closes gh-7293

Closes gh-7292

Closes gh-7291

Closes gh-7290

Closes gh-7289

Closes gh-7288

Closes gh-7287

Closes gh-7286

Closes gh-7285

Closes gh-7284

Closes gh-7283

Closes gh-7282

Closes gh-7281

See gh-5137

If the resource chain is used, such as by using the
`"spring.resources.chain.strategy.content.enabled"` property,
resource chain caching can prevent the developer from seeing
changes made to resources, so that caching should be disabled
when DevTools is enabled.

This commit sets the `"spring.resources.chain.cache"` property
to `true` when devtools is enabled.

See gh-7275

Closes gh-7189
See gh-6884

Closes gh-6985

See gh-6973

See gh-7054

Closes gh-6973

Closes gh-7054

Previously, there were two problems with servlet context initializer
beans that are a scoped proxy:

1. When there's no explicit registration bean the target of the scoped
   proxy is registered rather than the proxy. This meant that the
   proxy had no effect as it was being bypassed.
2. When there is an explicit registration bean, the registration is
   performed twice: the faulty implicit registration described above
   and explicit registration.

A fix (SPR-14816) has been made in Spring Framework so that we can
correctly determine the type of bean that will be produced by a
scoped proxy's factory bean. That change, coupled with the change in
this commit that ignored beans that are the target of a scoped proxy
addresses both of the problems described above. A single registration
is now performed and its the scoped proxy, rather than its target,
that is registered.

Closes gh-7150

Closes gh-7247

Update `DevToolsPropertyDefaultsPostProcessor` so that property defaults
are only added at development time. Properties are now added only when
`Restarter` is initialize or remote devtools is enabled.

Fixes gh-7014

* pr/7066:
  Support ApplicationReadyEvent from PidFileWriter

Update `ApplicationPidFileWriter` to support `ApplicationReadyEvent` in
addition to the already supported `ApplicationEnvironmentPreparedEvent`
and `ApplicationPreparedEvent` events.

Closes gh-7066
Fixes gh-7027

* pr/7217:
  Respect 'primary' flag when replacing databases

Update TestDatabaseAutoConfiguration to ensure that the the `primary`
flag of the `BeanDefinition` is copied.

Closes gh-7217

Update JpaBaseConfiguration so that the persistenceUnitRootLocation is
no longer detected. The update to gh-7003 means that we can now rely on
the standard detection mechanism.

Fixes gh-6983
See gh-6635

Fix ResourceHttpRequestHandler to set the ServletContext following the
Spring Framework update for SPR-14851.

Previously, if Boot's JarURLConnection pointed to the root of a nested
entry, e.g. /BOOT-INF/classes, a call to getInputStream() would throw
an IOException. This behavior is reasonable for a URL that points
to the root of a normal jar as the jar itself is on the class path
anyway. However, for a nested jar it meant that a call to
ClassLoader.getResources("") would not include URLs for any nested
jars and directories (/BOOT-INF/classes and jars in /BOOT-INF/lib).
This is due to some logic in URLClassPath.Loader.findResource that
verifies a URL by opening a connection and calling getInputStream().

The result of missing URLs for the root of nested jars and directories
is that classpath scanning that scans from the root (not a good idea
for performance reasons, but something that we should support) would
not find entries in /BOOT-INF/classes or in jars in /BOOT-INF/lib.

This commit updates our JarURLConnection so that it no longer throws
an IOException when asked for an InputStream for the root of a nested
entry (directory or jar).

Fixes gh-7003