Make bootstrap.sh more friendly to other shells. (#27392)

* Make bootstrap.sh more friendly to other shells.

I found some CI systems trying to use dash, and that does not
seem to work at all due to it not understanding '<<<' or `[[`.

Dash is still not ok because overall because arguments to `.` do
not get passed along, however it would work as a default.

Changes:
  - loop using IFS (and set sh_word_split for ZSH)
  - replaced `[[` tests with `[`

* Restyle

* Remove quoting logic that breaks execution

* Stop restyling bootstrap.sh

* Fix path

* Do not permanently alter zsh options, use local_options

* update sh_word_split to shwordsplit. Both seem to work, the non-underscore seems more common in docs

.restyled.yaml

@@ -80,6 +80,7 @@ exclude:
     - "zzz_generated/**/*" # already clang-formatted by our zap tooling
     - "src/controller/java/generated/java/**/*" # not formatted: generated files
     - "src/controller/java/zap-generated/**/*" # not formatted: generated files
+    - "scripts/setup/bootstrap.sh" # tries to quote loop variable
 
 
 changed_paths:

scripts/setup/bootstrap.sh

@@ -19,7 +19,7 @@ _install_additional_pip_requirements() {
     shift
 
     # figure out additional pip install items
-    while [[ $# -gt 0 ]]; do
+    while [ $# -gt 0 ]; do
         case $1 in
             -p | --platform)
                 _SETUP_PLATFORM=$2
@@ -32,13 +32,14 @@ _install_additional_pip_requirements() {
         esac
     done
 
-    if ! [ -z "$_SETUP_PLATFORM" ]; then
+    if [ -n "$_SETUP_PLATFORM" ]; then
+        _OLD_IFS=$IFS
+        IFS=","
         if [ -n "$ZSH_VERSION" ]; then
-            IFS="," read -r -A _PLATFORMS <<<"$_SETUP_PLATFORM"
-        else
-            IFS="," read -r -a _PLATFORMS <<<"$_SETUP_PLATFORM"
+            setopt local_options shwordsplit
         fi
-        for platform in "${_PLATFORMS[@]}"; do
+
+        for platform in ${_SETUP_PLATFORM}; do
             # Allow none as an alias of nothing extra installed (like -p none)
             if [ "$platform" != "none" ]; then
                 echo "Installing pip requirements for $platform..."
@@ -47,6 +48,8 @@ _install_additional_pip_requirements() {
                     -c "$_CHIP_ROOT/scripts/setup/constraints.txt"
             fi
         done
+        IFS=$_OLD_IFS
+        unset _OLD_IFS
         unset _PLATFORMS
     fi