Update README and optional package requirement

Changes:
    - Remove packages from README as they are redundant
      since the requirements.txt has all the required
      packages.
    - Added requirements_optional.txt for DMTF tools
      based packages

Tested:
    - Checked installation on sandbox and sanity test
      run on Python 3.12
      Robot Framework 7.2.2 (Python 3.12.9 on linux)

Change-Id: If6c6777e4efde7d012e87c786cd05e446606305d
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/requirements_optional.txt b/requirements_optional.txt
new file mode 100644
index 0000000..af239ca
--- /dev/null
+++ b/requirements_optional.txt
@@ -0,0 +1,8 @@
+aenum==3.1.15
+colorama==0.4.6
+pyasn1==0.6.1
+pyasn1_modules==0.4.1
+requests==2.32.3
+sseclient-py==1.8.0
+urllib3==1.26.20
+