Move Polaris client into root dir (#1172)

* Move python client into root dir

* Fix paths for regtests

* Fix path for notebooks and docs

* Change the path within container for consistency

* Add License Header

* Fix the copy folder cmd to restore the original regtests layout

* Rearrange dir layout inside docker

Author: liamzwbao

.gitignore

@@ -22,7 +22,7 @@ regtests/metastore_db
 regtests/output/
 # This file, if checked in after running for example regtests, contains unmanaged dependencies that eventually
 # cause unnecessary "security alerts" like https://github.com/apache/polaris/pull/718.
-regtests/client/python/poetry.lock
+client/python/poetry.lock
 
 # Python stuff (see note about poetry.lock above as well!)
 /poetry.lock

build.gradle.kts

@@ -107,7 +107,7 @@ tasks.named<RatTask>("rat").configure {
   excludes.add("regtests/.env")
   excludes.add("regtests/derby.log")
   excludes.add("regtests/metastore_db/**")
-  excludes.add("regtests/client/python/.openapi-generator/**")
+  excludes.add("client/python/.openapi-generator/**")
   excludes.add("regtests/output/**")
 
   excludes.add("**/*.ipynb")