Iterate on C/Python bindings documentation. (#14482)

Mostly updates to the C API page:

* Added code snippets for compiler and runtime APIs (real code minus
error handling, next to links to buildable templates/samples)
* Added more links to template repos and samples (including new
[iree-org/iree-template-compiler-cmake/](https://github.com/iree-org/iree-template-compiler-cmake/)
and
[iree-org/iree-template-runtime-cmake/](https://github.com/iree-org/iree-template-runtime-cmake/))
* Added diagram for runtime high level API concepts, simplified compiler
API concepts diagram
* Added more explanations about API concepts

Other changes:

* Tweaked Python bindings page to match C API bindings structure
* Enabled `navigation.tabs.sticky` mkdocs setting, keeping the
navigation tabs visible even after scrolling (since I expect users will
want to switch between guides and reference pages)

| | |
| -- | -- |
Current site | https://openxla.github.io/iree/reference/bindings/c-api/
Preview | https://scotttodd.github.io/iree/reference/bindings/c-api/

docs/website/mkdocs.yml

diff --git a/docs/website/mkdocs.yml b/docs/website/mkdocs.yml
index 70fdadb..1b6a147 100644
--- a/docs/website/mkdocs.yml
+++ b/docs/website/mkdocs.yml
@@ -19,20 +19,18 @@
 
   features:
     - content.code.annotate # Allow inline annotations
-    - content.code.copy     # Enable copy button
-    - content.tabs.link     # Link content tabs across site (e.g. Windows/Linux)
+    - content.code.copy # Enable copy button
+    - content.tabs.link # Link content tabs across site (e.g. Windows/Linux)
 
-    - navigation.instant  # Ajax-style dynamic loading (faster)
+    - navigation.instant # Ajax-style dynamic loading (faster)
     - navigation.tracking # Update URL in address bar with the active anchor
     - navigation.sections # Group sections without collapsible buttons
-    - navigation.expand   # Start sections expanded
-    - navigation.tabs     # Show primary sections in tabs below the header
-    - navigation.top      # "Back to top" button
+    - navigation.expand # Start sections expanded
+    - navigation.tabs # Show primary sections in tabs below the header
+    - navigation.tabs.sticky # Keep tabs visible at the top when scrolled
+    - navigation.top # "Back to top" button
     - navigation.indexes  # Section names can link to index.md pages
 
-    # Disabled options (consider enabling as the site changes)
-    # - navigation.tabs.sticky # Keep tabs visible at the top when scrolled
-
     - toc.follow # Scroll the TOC panel to follow the reader
 
   palette: