Move YAPF style setting to a project-wide .style.yapf file (#1038)

Scripts and workflows that run `yapf` currently each add the option
`--style=google` to the invocation of `yapf`. To follow best practices,
this PR adds a `.style.yapf` configuration file at the top level of the
project to set the style, and removes the flag from where it was added
on the command line explicitly.

The use of a config file has the following benefits:

- It lets tools like IDEs discover the setting automatically.
- It reduces the chances that developers will forget to add the flag
when they run `yapf` directly on the command line for quick checks, or
write new scripts that use `yapf`.
- It communicates intentions more clearly to new contributors.

Removing the flag from the scripts is not strictly necessary (everything
will work the same if there is both a config file and the flag is passed
to `yapf`). However, if a config file is used, it's better for
maintainability and consistency to also remove the flag from individual
invocations.

Note: the CI will fail the lint check until PR #1047 is merged.

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: mhucka

.style.yapf

@@ -0,0 +1,2 @@
+[style]
+based_on_style = google

scripts/format_all.sh

@@ -14,8 +14,7 @@
 # limitations under the License.
 # ==============================================================================
 echo "Doing python language formatting..."
-python3 -m yapf --style=google --in-place --recursive --parallel \
-  ./benchmarks ./scripts ./tensorflow_quantum
+python3 -m yapf --in-place --recursive ./benchmarks ./tensorflow_quantum ./scripts
 echo -e "Done! \nDoing notebook formatting..."
 python3 ./scripts/format_ipynb.py
 echo -e "Done! \nDoing C++ formatting..."

scripts/format_check.sh

@@ -72,7 +72,7 @@ for changed_file in ${changed_files}; do
     )
     if [[ "${changed_line_ranges}" != "--lines=0-0 " ]]; then
         # Do the formatting.
-        results=$(yapf --style=google --diff "${changed_file}" ${changed_line_ranges})
+        results=$(python3 -m yapf --diff "${changed_file}" ${changed_line_ranges})
 
         # Print colorized error messages.
         if [ ! -z "${results}" ]; then