[FEA] Improve Scala 2.13 build process to not require building against unstaged git changes

[NVnavkumar]

This is a follow on to #1525. The changes in #8592 do not address a concern in the build process in that the CI will build against unstaged git changes. See this thread:

#8592 (comment)

We should generate the pom files directly, and we can put the generated pom files in gitignore, so the CI will be able to build against what it sees as a clean working copy.

Note the CI will not be building Scala 2.13 artifacts until this issue is addressed.

[gerashegalov]

archetype could be an interesting option for pom generation. We may even be able to use it for generating classes like

/*** spark-rapids-shim-json-lines
{"spark": "331"}
spark-rapids-shim-json-lines ***/
package com.nvidia.spark.rapids.spark331

import org.apache.spark.SparkConf
import org.apache.spark.sql.rapids.shims.spark331.ProxyRapidsShuffleInternalManager

/** A shuffle manager optimized for the RAPIDS Plugin for Apache Spark. */
sealed class RapidsShuffleManager(
    conf: SparkConf,
    isDriver: Boolean) extends ProxyRapidsShuffleInternalManager(conf, isDriver) {
}