Fixes necessary to compile z3 included in clang-tidy via FetchContents. (#9768)

The page
https://github.com/Z3Prover/z3/blob/master/README-CMake.md#adding-z3-as-a-dependency-to-a-cmake-project
advises using the CMake FetchContent feature to include z3 as source
into other CMake project. I'm trying to do this to use Z3 within a
ClangTidy checker. This is one of a series of PR's aimed at getting Z3
to compile cleanly when included this way.

This initial PR fixes all the errors, allowing the compilation to
succeed. Subsequent diffs will address warnings.

I tested only the CMake compilation, on a Mac.

*Missing Z3_THROWs*

Update z3++.h to use Z3_THROW in a couple of places. Clang compiles with
exceptions disabled so we get messages like:

```
/Users/daviddetlefs/llvm-project/build_dbg/_deps/z3-src/src/api/c++/z3++.h:4928:17: error: cannot use 'throw' with exceptions disabled4928 |                 throw exception("rcf_num objects from different contexts");
```

NOTE TO REVIEWERS: I'm not complete clear on the usage conventions for
Z3_THROW. With exception disabled, it seems like the throwing function
will just continue. If there's somethign else that should be done, like
setting some error state, please let me know.

*CMake component name collision*

There was an error at the CMake level, a name collision (on "opt").
Apparently CMake components are named using a flat namespace, so it's
easy to see how this could occur. It seems to me that the right global
way to fix this would be to encourage people to use some form of
"qualified name" convention in naming their component. The fix I chose
was a local version of this, changing the Z3 component name to z3_opt.
(It didn't seem feasible to make the change in clang.)

NOTE TO REVIEWERS: If you think this is OK, please let me know if

a) You'd like me to also change the name of the opt directory, to keep
thecomponent-name == directory-name invariant, and

b) You'd like me to make this z3_ change more globally, to future-proof
(somewhat) against similar component name collisions.

src/api/CMakeLists.txt

@@ -66,7 +66,7 @@ z3_add_component(api
     z3_replayer.cpp
     ${full_path_generated_files}
   COMPONENT_DEPENDENCIES
-    opt
+    z3_opt
     euf
     portfolio
     realclosure

src/api/c++/z3++.h

@@ -4925,7 +4925,7 @@ namespace z3 {
         
         void check_context(rcf_num const& other) const {
             if (m_ctx != other.m_ctx) {
-                throw exception("rcf_num objects from different contexts");
+                Z3_THROW(exception("rcf_num objects from different contexts"));
             }
         }
         
@@ -5105,9 +5105,9 @@ namespace z3 {
     */
     inline std::vector<rcf_num> rcf_roots(context& c, std::vector<rcf_num> const& coeffs) {
         if (coeffs.empty()) {
-            throw exception("polynomial coefficients cannot be empty");
+            Z3_THROW(exception("polynomial coefficients cannot be empty"));
         }
-        
+
         unsigned n = static_cast<unsigned>(coeffs.size());
         std::vector<Z3_rcf_num> a(n);
         std::vector<Z3_rcf_num> roots(n);

src/opt/CMakeLists.txt

@@ -1,4 +1,4 @@
-z3_add_component(opt
+z3_add_component(z3_opt
   SOURCES
     maxcore.cpp
     maxlex.cpp

src/shell/CMakeLists.txt

@@ -8,7 +8,7 @@ set (shell_object_files "")
 
 # We are only using these dependencies to enforce a build
 # order. We don't use this list for actual linking.
-set(shell_deps api extra_cmds opt sat)
+set(shell_deps api extra_cmds z3_opt sat)
 z3_expand_dependencies(shell_expanded_deps ${shell_deps})
 get_property(Z3_LIBZ3_COMPONENTS_LIST GLOBAL PROPERTY Z3_LIBZ3_COMPONENTS)
 foreach (component ${Z3_LIBZ3_COMPONENTS_LIST})