[SPARK-18276][ML] ML models should copy the training summary and set parent

## What changes were proposed in this pull request?

Only some of the models which contain a training summary currently set the summaries in the copy method. Linear/Logistic regression do, GLR, GMM, KM, and BKM do not. Additionally, these copy methods did not set the parent pointer of the copied model. This patch modifies the copy methods of the four models mentioned above to copy the training summary and set the parent.

## How was this patch tested?

Add unit tests in Linear/Logistic/GeneralizedLinear regression and GaussianMixture/KMeans/BisectingKMeans to check the parent pointer of the copied model and check that the copied model has a summary.

Author: sethah <seth.hendrickson16@gmail.com>

Closes #15773 from sethah/SPARK-18276.

(cherry picked from commit 23ce0d1e)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>