Closes gh-23439

See gh-23433

Closes gh-23433

See gh-22983

Previously LOG_LEVEL_PATTERN and LOG_DATEFORMAT_PATTERN were not
consumed as system properties in log4j2.xml and log4j2-file.xml. As a
result, the logging.pattern.level and logging.pattern.dateformat
configuration properties, which are translated into the
LOG_LEVEL_PATTERN and LOG_DATEFORMAT_PATTERN system properties
respectively had no effect.

This commit updates the log4j2.xml and log4j2-file.xml config files to
consume LOG_LEVEL_PATTERN and LOG_DATEFORMAT_PATTERN as system
properties. When the system property is not set, the configuation falls
back to the default values specified in the config files. Tests for
both log4j2.xml and log4j2-file.xml to verify the behaviour have also
bean added.

Fixes gh-22983

Closes gh-23425

* gh-23418:
  Polish "Add note about Kotlin main class name"
  Add note about Kotlin main class name

Closes gh-23418

See gh-23418

See gh-23418

Closes gh-23416

Closes gh-23415

Previously, spring.flyway.init-sqls was only applied to Flyway's
configuration if Flyway was being configured to create the DataSource.
If Flyway was being configured to use an existing DataSource, init-sqls
was not applied. This is a hangover from when the init SQLs support was
introduced. At that time, Flyway only supported SQL to initialize the
connection when it was creating the DataSource. Flyway 5.2 added init
SQL support no matter how Flyway's DataSource was configured.

This commit updates FlywayAutoConfiguration to always apply the
init-sqls property to Flyway's configuration. The property's
documentation does not describe the current limitation so this change
should align the behaviour with what the documentation leads people to
expect.

Fixes gh-23392

Fixes gh-23402

Closes gh-23388

Closes gh-23186

Closes gh-23384

Closes gh-23185

Closes gh-23198

Closes gh-23374

Closes gh-23375

Closes gh-23374

Closes gh-23372

Closes gh-23371

Closes gh-23195

Closes gh-23194

Closes gh-23340

Closes gh-23336

Closes gh-23335