Add logic to support searching for azcopy on linux

Author: kananb

src/cli/onefuzz/azcopy.py

@@ -5,18 +5,19 @@
 
 def find_azcopy() -> str:
     azcopy = os.environ.get("AZCOPY")
+    binary_name = "azcopy" if os.name == "posix" else "azcopy.exe"
 
     if azcopy:
         if not os.path.exists(azcopy):
             raise Exception(f"AZCOPY environment variable is invalid: {azcopy}")
         elif os.path.isdir(azcopy):
-            contains_azcopy = os.path.isfile(os.path.join(azcopy, "azcopy.exe"))
+            contains_azcopy = os.path.isfile(os.path.join(azcopy, binary_name))
 
             if contains_azcopy:
-                azcopy = os.path.join(azcopy, "azcopy.exe")
+                azcopy = os.path.join(azcopy, binary_name)
             else:
                 raise Exception(
-                    f"The directory specified by AZCOPY doesn't contain the file 'azcopy.exe': {azcopy}"
+                    f"The directory specified by AZCOPY doesn't contain the file '{binary_name}': {azcopy}"
                 )
     else:
         azcopy = shutil.which("azcopy")