Implement two metaflags for minimal bulds

[The9Cat]

The issue

Default builds of EXP for applications or pyEXP only has too many unnecessary install targets.

Proposed solution

Enabled two CMake flags that allow flavors of minimal bulds

1. ENABLE_MINIMAL compiles only libexpui and libexputils and necessary submodule librarires with no binaries, etc.
2. ENABLE_PYEXP_ONLY compiles only the libraries needed for the pyEXP module with no binaries

Tests

• Both flavors compile and install as expected
• The ENABLE_MINIMAL works with the current Gala interface
• The ENABLE_PYTHON_ONLY provides a complete and working pyEXP module

[Copilot]

Pull Request Overview

This PR introduces two metaflags to enable minimal builds of EXP, reducing unnecessary install targets for specific use cases. The metaflags allow users to compile only the libraries needed for either basic EXP support or Python bindings.

• Adds ENABLE_MINIMAL flag to compile only core support libraries (libexpui and libexputils)
• Adds ENABLE_PYEXP_ONLY flag to compile only libraries needed for the pyEXP Python module
• Conditionalizes utility compilation with ENABLE_UTILS flag

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
CMakeLists.txt	Adds two new metaflags (ENABLE_MINIMAL and ENABLE_PYEXP_ONLY) that configure other build options, and conditionalizes subdirectory builds
expui/CMakeLists.txt	Wraps utility executable compilation in ENABLE_UTILS conditional block

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[lgarrison]

Thanks! Everything looks good to me; with ENABLE_MINIMAL, EXP builds only the targets that Gala-EXP needs. The Gala tests pass, too. The pyEXP extension seems to work correctly with ENABLE_PYEXP_ONLY as well.

[michael-petersen]

Looks great to me -- no build problems here for me either, so I'll merge this in.