Add qmlImportPaths property to .pyproject file

Users should be able to add custom QML import paths for
Python/PySide2/PyQt5 projects in Qt Creator in order to
get syntax highlighting and code completion for custom
QML modules.

Fixes: QTCREATORBUG-23679
Change-Id: Iec7c691c4b8709c48a790cd27ac7c6e755967796
Reviewed-by: hjk <hjk@qt.io>

tests/manual/python/pyproject/pyproject.pyproject

@@ -0,0 +1,9 @@
+{
+    "files": [
+        "main.py",
+        "main.qml"
+    ],
+    "qmlImportPaths": [
+        "./imports"
+    ]
+}