Add Ghidra function import script (#909)

* Add draft for Ghidra function import script

* feature: Basic PDB analysis [skip ci]

This is a draft with a lot of open questions left. Please do not merge

* Refactor: Introduce submodules and reload remedy

* refactor types and make them Python 3.9 compatible

* run black

* WIP: save progress

* fix types and small type safety violations

* fix another Python 3.9 syntax incompatibility

* Implement struct imports [skip ci]

- This code is still in dire need of refactoring and tests
- There are only single-digit issues left, and 2600 functions can be imported
- The biggest remaining error is mismatched stacks

* Refactor, implement enums, fix lots of bugs

* fix Python 3.9 issue

* refactor: address review comments

Not sure why VS Code suddenly decides to remove some empty spaces, but they don't make sense anyway

* add unit tests for new type parsers, fix linter issue

* refactor: db access from pdb_extraction.py

* Fix stack layout offset error

* fix: Undo incorrect reference change

* Fix CI issue

* Improve READMEs (fix typos, add information)

---------

Co-authored-by: jonschz <jonschz@users.noreply.github.com>

tools/ghidra_scripts/README.md

@@ -0,0 +1,25 @@
+# Ghidra Scripts
+
+The scripts in this directory provide additional functionality in Ghidra, e.g. imports of symbols and types from the PDB debug symbol file.
+
+## Setup
+
+### Ghidrathon
+Since these scripts and its dependencies are written in Python 3, [Ghidrathon](https://github.com/mandiant/Ghidrathon) must be installed first. Follow the instructions and install a recent build (these scripts were tested with Python 3.12 and Ghidrathon v4.0.0).
+
+### Script Directory
+- In Ghidra, _Open Window -> Script Manager_.
+- Click the _Manage Script Directories_ button on the top right.
+- Click the _Add_ (Plus icon) button and select this file's parent directory.
+- Close the window and click the _Refresh_ button.
+- This script should now be available under the folder _LEGO1_.
+
+### Virtual environment
+As of now, there must be a Python virtual environment set up under `$REPOSITORY_ROOT/.venv`, and the dependencies of `isledecomp` must be installed there, see [here](../README.md#tooling).
+
+## Development
+- Type hints for Ghidra (optional): Download a recent release from https://github.com/VDOO-Connected-Trust/ghidra-pyi-generator,
+  unpack it somewhere, and `pip install` that directory in this virtual environment. This provides types and headers for Python.
+  Be aware that some of these files contain errors - in particular, `from typing import overload` seems to be missing everywhere, leading to spurious type errors.
+- Note that the imported modules persist across multiple runs of the script (see [here](https://github.com/mandiant/Ghidrathon/issues/103)).
+  If you indend to modify an imported library, you have to use `import importlib; importlib.reload(${library})` or restart Ghidra for your changes to have any effect. Unfortunately, even that is not perfectly reliable, so you may still have to restart Ghidra for some changes in `isledecomp` to be applied.