feat(sam): check for sam cli in /opt/homebrew/

Problem:
On macos ARM (M1) systems, homebrew installs to `/opt/homebrew` instead
of `/usr/local`. But `UnixSamCliLocator` doesn't check this, so
1. it searches $PATH (slow)
2. won't find `sam` if `/opt/homebrew` is not in $PATH for some reason

Solution:
Add `/opt/homebrew` to `UnixSamCliLocator`.

Author: justinmk3

src/shared/sam/cli/samCliLocator.ts

@@ -177,6 +177,7 @@ class WindowsSamCliLocator extends BaseSamCliLocator {
 
 class UnixSamCliLocator extends BaseSamCliLocator {
     private static readonly locationPaths: string[] = [
+        '/opt/homebrew/bin/sam',
         '/usr/local/bin',
         '/usr/bin',
         // WEIRD BUT TRUE: brew installs to /home/linuxbrew/.linuxbrew if