Add techjedi's image import script (#4171)

## What type of PR is this? (check all applicable)

- [X ] Feature

## Have you discussed this change with the InvokeAI team?
- [X] Yes

## Have you updated all relevant documentation?
- [X] Yes

## Description

This PR adds the `invokeai-import-images` script, which imports a
directory of 2.*.* -generated images into the current InvokeAI root
directory, preserving and converting their metadata. The script also
handles 3.* images.

Many thanks to @techjedi for writing this. This version differs from the
original in two minor respects:

1. It is installed as an `invokeai-import-images` command.
2. The prompts for image and database paths use file completion provided
by the `prompt_toolkit` library.
## To Test

1. Activate the virtual environment for the destination root to import
INTO
2. Run `invokeai-import-images`
3. Follow the prompts

## Related Tickets & Documents

This is a frequently-requested feature on Discord, but I couldn't find
an Issue.

## QA Instructions, Screenshots, Recordings

<!-- 
Please provide steps on how to test changes, any hardware or 
software specifications as well as any other pertinent information. 
-->

## Added/updated tests?

- [ ] Yes
- [X] No : but should in the future

Author: lstein

README.md

@@ -306,13 +306,30 @@ InvokeAI. The second will prepare the 2.3 directory for use with 3.0.
 You may now launch the WebUI in the usual way, by selecting option [1]
 from the launcher script
 
-#### Migration Caveats
+#### Migrating Images
 
 The migration script will migrate your invokeai settings and models,
 including textual inversion models, LoRAs and merges that you may have
 installed previously. However it does **not** migrate the generated
-images stored in your 2.3-format outputs directory. You will need to
-manually import selected images into the 3.0 gallery via drag-and-drop.
+images stored in your 2.3-format outputs directory. To do this, you 
+need to run an additional step:
+
+1. From a working InvokeAI 3.0 root directory, start the launcher and
+enter menu option [8] to open the "developer's console".
+
+2. At the developer's console command line, type the command:
+
+```bash
+invokeai-import-images
+```
+
+3. This will lead you through the process of confirming the desired
+   source and destination for the imported images. The images will
+   appear in the gallery board of your choice, and contain the
+   original prompt, model name, and other parameters used to generate
+   the image.
+   
+(Many kudos to **techjedi** for contributing this script.)
 
 ## Hardware Requirements
 

docs/installation/010_INSTALL_AUTOMATED.md

@@ -264,7 +264,7 @@ experimental versions later.
 	  you can create several levels of subfolders and drop your models into
       whichever ones you want.
 	
-    - ***Autoimport FolderLICENSE***     
+    - ***LICENSE***     
 
     At the bottom of the screen you will see a checkbox for accepting
     the CreativeML Responsible AI Licenses. You need to accept the license