Use the src/ layout to fix packaging Khoj for PyPi

- Why
  The khoj pypi packages should be installed in `khoj' directory.
  Previously it was being installed into `src' directory, which is a
  generic top level directory name that is discouraged from being used

- Changes
 - move src/* to src/khoj/*
 - update `setup.py' to `find_packages' in `src' instead of project root
 - rename imports to form `from khoj.*' in complete project
 - update `constants.web_directory' path to use `khoj' directory
 - rename root logger to `khoj' in `main.py'
 - fix image_search tests to use the newly rename `khoj' logger
 - update config, docs, workflows to reference new path `src/khoj'

tests/data/markdown/interface_emacs_readme.md

@@ -28,7 +28,7 @@
         ;; Khoj Package for Semantic Search
         (use-package khoj
           :after org
-          :straight (khoj :type git :host github :repo "debanjum/khoj" :files (:defaults "src/interface/emacs/khoj.el"))
+          :straight (khoj :type git :host github :repo "debanjum/khoj" :files (:defaults "src/khoj/interface/emacs/khoj.el"))
           :bind ("C-c s" . 'khoj))
         ```
 -   With [Quelpa](https://github.com/quelpa/quelpa#installation)

tests/data/markdown/main_readme.md

@@ -6,8 +6,8 @@
 *Allow natural language search on user content like notes, images,
 transactions using transformer ML models*
 
-User can interface with Khoj via [Web](./src/interface/web/index.html),
-[Emacs](./src/interface/emacs/khoj.el) or the API. All search is done
+User can interface with Khoj via [Web](./src/khoj/interface/web/index.html),
+[Emacs](./src/khoj/interface/emacs/khoj.el) or the API. All search is done
 locally[\*](https://github.com/debanjum/khoj#miscellaneous)
 
 ## Demo
@@ -47,8 +47,8 @@ just generating embeddings*
     -   [Update Index](http://localhost:8000/api/update?t=ledger)
     -   [Configure Application](https://localhost:8000/ui)
 -   **Khoj via Emacs**
-    -   [Install](https://github.com/debanjum/khoj/tree/master/src/interface/emacs#installation)
-        [khoj.el](./src/interface/emacs/khoj.el)
+    -   [Install](https://github.com/debanjum/khoj/tree/master/src/khoj/interface/emacs#installation)
+        [khoj.el](./src/khoj/interface/emacs/khoj.el)
     -   Run `M-x khoj <user-query>`
 
 ## Run Unit tests
@@ -118,7 +118,7 @@ docker-compose build --pull
     images, transactions etc specified in config YAML
 
     ``` shell
-    python3 -m src.main -c=config/khoj_sample.yml -vv
+    python3 -m src.khoj.main -c=config/khoj_sample.yml -vv
     ```
 
 ### Upgrade On Local Machine