Add documentation and scripts for comparing builds using UnityDataTool (#27)

Comparison of builds is a very common topic when trying to investigate non-determinism or other "unexpected" changes when a project is built. But there is no single "compare builds" tool or feature and UnityDataTools doesn't natively support comparison.

This PR adds two "example" scripts that aid in the comparison of the sqlite database generated by "UnityDataTools analyze".
It also frames the use of these scripts in a new documentation topic that also gets into using diff tools + WebExtract + UnityDataTools.

The two examples try to touch on two common tricky scenarios:

AssetBundles built by Addressables with hashes in the name
texture changes inside .resS files

Co-authored-by: Tim Thomas <timt@unity3d.com>

Author: SkowronskiAndrew

Documentation/AddressableBuildComparison.png

@@ -214,6 +214,10 @@ object_id             type         name            pretty_size  crc32
 3866367853307903194   Sprite       red             460.0 B      1811343945
 ```
 
+## Example: Finding differences between two builds
+
+This is a large subject, see [Comparing Builds](comparing-builds.md).
+
 ## Example: Matching content back to the source asset
 
 UnityDataTool works on the output of a Unity build, which, by its very nature, only contains the crucial data needed to efficiently load built content in the Player.  So it does not include any information about the assets and scenes in the project that was used to create that build.  However you may want to match content back to the original source asset or scene.  For example if the size of an AssetBundle has unexpectedly changed between builds then you may want to track down which source assets could be responsible for that change.  Or you may want to confirm that some particular image has been included in the build.