Refactor DataSourceBuilder and add derivedFrom

Refactor `DataSourceBuilder` to use direct property mappers rather than
the `Binder` and aliases. Supported DataSource types now include two-way
mappers which allows us to both get and set properties in a uniform way.

A new `derivedFrom` factory method has been added which allows a new
`DataSource` to be derived from an existing one. This update is
primarily to allow Flyway and Liquibase migrations to work against a
`@Bean` configured DataSource rather than assuming that the primary
DataSource was always created via auto-configuration.

See gh-25643

Author: philwebb

spring-boot-project/spring-boot/build.gradle

@@ -20,8 +20,10 @@ dependencies {
 	optional("com.atomikos:transactions-jms")
 	optional("com.atomikos:transactions-jta")
 	optional("com.fasterxml.jackson.core:jackson-databind")
+	optional("com.h2database:h2")
 	optional("com.google.code.gson:gson")
 	optional("com.oracle.database.jdbc:ucp")
+	optional("com.oracle.database.jdbc:ojdbc8")
 	optional("com.samskivert:jmustache")
 	optional("com.zaxxer:HikariCP")
 	optional("io.netty:netty-tcnative-boringssl-static")
@@ -58,6 +60,7 @@ dependencies {
 	optional("org.jboss:jboss-transaction-spi")
 	optional("org.jooq:jooq")
 	optional("org.liquibase:liquibase-core")
+	optional("org.postgresql:postgresql")
 	optional("org.slf4j:jul-to-slf4j")
 	optional("org.slf4j:slf4j-api")
 	optional("org.springframework:spring-messaging")
@@ -76,11 +79,9 @@ dependencies {
 
 	testImplementation(project(":spring-boot-project:spring-boot-tools:spring-boot-test-support"))
 	testImplementation("com.google.appengine:appengine-api-1.0-sdk")
-	testImplementation("com.h2database:h2")
 	testImplementation("com.ibm.db2:jcc")
 	testImplementation("com.jayway.jsonpath:json-path")
 	testImplementation("com.microsoft.sqlserver:mssql-jdbc")
-	testImplementation("com.oracle.database.jdbc:ojdbc8")
 	testImplementation("com.squareup.okhttp3:okhttp")
 	testImplementation("com.sun.xml.messaging.saaj:saaj-impl")
 	testImplementation("io.projectreactor:reactor-test")
@@ -97,7 +98,6 @@ dependencies {
 	testImplementation("org.mariadb.jdbc:mariadb-java-client")
 	testImplementation("org.mockito:mockito-core")
 	testImplementation("org.mockito:mockito-junit-jupiter")
-	testImplementation("org.postgresql:postgresql")
 	testImplementation("org.springframework:spring-context-support")
 	testImplementation("org.springframework.data:spring-data-redis")
 	testImplementation("org.springframework.data:spring-data-r2dbc")