Fixes rvlink/rvpush handler when installed outside of C:\ (AcademySoftwareFoundation#323)

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### Summarize your change.

Fixes the .bat files that install the rvlink/rvpush URL scheme handlers
by adding an extra \d to the cd calls so we change drive if required
with the change directory call (it's a Windows thing...)

### Describe the reason for the change.

@savoiei reported that if OpenRV is installed on another drive than the
OS drive (C:\ in most cases), the script fails with `Executable file
C:\Windows\bin\rv.exe does not exist. Exiting script.`

The reason behind that is that when cmd.exe starts from explorer.exe,
it's from the directory that contains cmd.exe, and then we try to cd to
the location of the script being executed, to locate rv.exe relative to
the script.

Adding \d tells the cd call to change both the path and the drive,
because they are two separate concepts on Windows.

### Describe what you have tested and on which operating system.

Tested on Windows.

### Add a list of changes, and note any that might need special
attention during the review.

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### If possible, provide screenshots.

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Signed-off-by: Kerby Geffrard <kerby.geffrard@autodesk.com>

Author: Kerby Geffrard

packages/rv/openwith.reg.bat

@@ -10,7 +10,7 @@ if %errorLevel% == 0 (
     exit /b
 )
 
-cd %~dp0
+cd /d %~dp0
 pushd ..
 
 REM Define the path to the executable

packages/rv/openwith_rvpush_merge.reg.bat

@@ -10,7 +10,7 @@ if %errorLevel% == 0 (
     exit /b
 )
 
-cd %~dp0
+cd /d %~dp0
 pushd ..
 
 REM Define the path to the executable

packages/rv/openwith_rvpush_set.reg.bat

@@ -10,7 +10,7 @@ if %errorLevel% == 0 (
     exit /b
 )
 
-cd %~dp0
+cd /d %~dp0
 pushd ..
 
 REM Define the path to the executable

packages/rv/rvlink.reg.bat

@@ -10,7 +10,7 @@ if %errorLevel% == 0 (
     exit /b    exit /b
 )
 
-cd %~dp0
+cd /d %~dp0
 pushd ..
 
 REM Define the path to the executable

packages/rv/rvlink_rvpush.reg.bat

@@ -10,7 +10,7 @@ if %errorLevel% == 0 (
     exit /b
 )
 
-cd %~dp0
+cd /d %~dp0
 pushd ..
 
 REM Define the path to the executable