Closes gh-21208

This commit upgrades to RSocket 1.0.0-RC7.
This new RC brings API changes we have to adapt to. As of this commit,
we're introducing a new `RSocketServerCustomizer` which replaces the now
deprecated `ServerRSocketFactoryProcessor`.

Closes gh-21046

Closes gh-21205

Closes gh-21204

Closes gh-21203

Closes gh-21202

Closes gh-21201

Closes gh-21200

Closes gh-21199

Closes gh-21198

Closes gh-21197

Closes gh-21196

Closes gh-21194

Closes gh-21193

Closes gh-21192

Closes gh-21191

Closes gh-21190

Closes gh-21189

Closes gh-21188

Closes gh-21187

Closes gh-21186

Closes gh-21185

Closes gh-21184

Closes gh-21183

Closes gh-21182

Closes gh-21181

Closes gh-21180

Closes gh-21179

Update `JarFile` so that `super.close()` is called early so that the
file is not left open. Since we re-implement `JarFile` methods to work
directly on the underlying `RandomAccessDataFile`, it should be safe
to close immediately.

Closes gh-21177

Closes gh-21175

Closes gh-21174

Update `ConfigFileApplicationListener` to throw a better exception if
`classpath*:` is used as a location.

Closes gh-21168

See gh-21170

This reverts commit 8404ae7f. The
long-shot didn't pay off.

Previously, the developmentOnly configuration, typically used for
Devtools, had to be declared manually. The BootJar and BootWar tasks
then had a property, excludeDevtools, that could be used to control
whether or not Devtools would be excluded from the executable archive.

This commit updates the reaction to the Java plugin being applied to
automatically create the developmentOnly configuration. The classpaths
of bootJar and bootWar are then configured not to include the contents
of the developmentOnly configuration. As a result of this, the
excludeDevtools property is no longer needed and has been deprecated.
Its default has also been changed from true to false to make it easy
to opt in to Devtools, when configured as a development-only
dependency, being included in executable jars and wars by adding
developmentOnly to the classpath of the archive task.

Closes gh-16599

Closes gh-20943