Core: Use Immutables for TableMetadata

The motivation for this change is
* `TableMetadata` is truly immutable
* we get a Builder for free, which allows easy creation of new `TableMetadata` instances

Author: nastra

baseline.gradle

@@ -63,8 +63,8 @@ subprojects {
   pluginManager.withPlugin('com.palantir.baseline-error-prone') {
     tasks.withType(JavaCompile).configureEach {
       options.errorprone.errorproneArgs.addAll (
-          // error-prone is slow, don't run on tests and generated src
-          '-XepExcludedPaths:.*/(test|generated-src)/.*',
+          // error-prone is slow, don't run on tests/generated-src/generated
+          '-XepExcludedPaths:.*/(test|generated-src|generated)/.*',
           // specific to Palantir
           '-Xep:ConsistentLoggerName:OFF',  // Uses name `log` but we use name `LOG`
           '-Xep:FinalClass:OFF',

build.gradle

@@ -204,6 +204,7 @@ project(':iceberg-common') {
 
 project(':iceberg-core') {
   dependencies {
+    annotationProcessor "org.immutables:value"
     api project(':iceberg-api')
     implementation project(':iceberg-common')
     implementation project(path: ':iceberg-bundled-guava', configuration: 'shadow')
@@ -212,6 +213,7 @@ project(':iceberg-core') {
       exclude group: 'org.tukaani' // xz compression is not supported
     }
 
+    implementation "org.immutables:value"
     implementation "com.fasterxml.jackson.core:jackson-databind"
     implementation "com.fasterxml.jackson.core:jackson-core"
     implementation "com.github.ben-manes.caffeine:caffeine"