Address invalid escape sequences in strings

The backslash character is an escape sequence in Python strings. These
strings contain backslashes which do not intend to escape the following
character, but rather include the backslash in the string.

There are two possible resolutions:
1. Make the string a "raw" string by prefixing it with "r". This
   effectively makes backslashes into a normal character.
2. Escape the backslashes with another backslash.

I used both approaches in this change where appropriate.

colcon_hardware_acceleration/subverb/__init__.py

@@ -408,7 +408,7 @@ def mount_rawimage(rawimage_path, partition=1, debug=False):
 
     # fetch UNITS
     units = None
-    cmd = "fdisk -l " + rawimage_path + " | grep 'Units\|Unidades' | awk '{print $8}'"
+    cmd = "fdisk -l " + rawimage_path + " | grep 'Units\\|Unidades' | awk '{print $8}'"
     outs, errs = run(cmd, shell=True)
     if outs:
         units = int(outs)
@@ -682,7 +682,7 @@ def copy_colcon_workspace(install_dir):  # noqa: D102
 
     # fetch UNITS
     units = None
-    cmd = "fdisk -l " + rawimage_path + " | grep 'Units\|Unidades' | awk '{print $8}'"
+    cmd = "fdisk -l " + rawimage_path + " | grep 'Units\\|Unidades' | awk '{print $8}'"
     outs, errs = run(cmd, shell=True)
     if outs:
         units = int(outs)
@@ -921,7 +921,7 @@ def fix_yocto_honister(partition=2):  # noqa: D102
     - /etc/profile.d/ros/setup.sh and
     - /usr/bin/ros_setup.bash
     """
-    content_etc_profile = """
+    content_etc_profile = r"""
 # generated from ament_package/template/prefix_level/setup.sh.in
 
 # since this file is sourced use either the provided AMENT_CURRENT_PREFIX
@@ -1068,7 +1068,7 @@ def fix_yocto_honister(partition=2):  # noqa: D102
 unset AMENT_SHELL
 """
 
-    content_usr_bin = """
+    content_usr_bin = r"""
 # copied from ament_package/template/prefix_level/setup.bash
 
 AMENT_SHELL=bash

colcon_hardware_acceleration/subverb/emulation.py

@@ -276,7 +276,7 @@ def prepare_emulation(self, context):  # noqa: D102
             cmd = (
                 "fdisk -l "
                 + rawimage_path
-                + " | grep 'Units\|Unidades' | awk '{print $8}'"
+                + " | grep 'Units\\|Unidades' | awk '{print $8}'"
             )
             outs, errs = run(cmd, shell=True)
             if outs: