Implementation of basic data flow analysis for PowerPC (#212)

* WIP implementation

* * Move flow analysis to dedicated file
* Show string constants inline
* Handle calls to MWCC "sled" helpers which otherwise disrupt flow analysis

* Run cargo insta review

* Apply clippy feedback

* Update more tests.

* Remove std use from ppc flow analysis

* Try to make wasm build work again

* More test changes

* Probably last wasm fix

* Formatting

* Fix WASM

* One more clippy thing

* Fixed display of float constants in a LFS or LFD instruction in case where there is a branch to the subsequent instruction with a different register value.

* On lines with a reloc, only hide Symbol type data flow values rather than all data flow values.

* Formatting

objdiff-cli/src/views/function_diff.rs

@@ -570,6 +570,7 @@ impl FunctionDiffUi {
                     DiffTextColor::Normal => Color::Gray,
                     DiffTextColor::Dim => Color::DarkGray,
                     DiffTextColor::Bright => Color::White,
+                    DiffTextColor::DataFlow => Color::LightCyan,
                     DiffTextColor::Replace => Color::Cyan,
                     DiffTextColor::Delete => Color::Red,
                     DiffTextColor::Insert => Color::Green,