Add rocprofiler_load_counter_definition (#1193)

Adds rocprofiler_load_counter_definition. This function allows a counter definition file to be supplied to rocprofiler-sdk directly. Takes in a string containing the counter definition YAML, its size (in bytes), and a flag value to state whether this is an append operation or not.

---------

Co-authored-by: Benjamin Welton <ben@amd.com>
Co-authored-by: Jonathan R. Madsen <jrmadsen@users.noreply.github.com>
Co-authored-by: usrihari123 <srihari.u@amd.com>

source/docs/how-to/using-rocprofv3.rst

@@ -126,6 +126,10 @@ Here is the sample of commonly used ``rocprofv3`` command-line options. Some opt
     - List metrics for counter collection.
     - Kernel Dispatch Counter Collection
 
+  * - ``-E`` \| ``--extra_counters``
+    - Specifies the path to a YAML file containing extra counter definitions.
+    - Kernel Dispatch Counter Collection
+
   * - ``-M`` \| ``--mangled-kernels``
     - Overrides the default demangling of kernel names.
     - Output control
@@ -733,6 +737,18 @@ To supply the counters via ``command-line`` options, use:
    1. Please note that more than 1 counters should be separated by a space or a comma.
    2. Job will fail if entire set of counters cannot be collected in single pass
 
+Extra-counters
+++++++++++++++++
+
+Counters with custom definitions can be defined through an extra_counters.yaml 
+file using the ``command-line`` option.
+
+To supply the extra counters via ``command-line`` options, use:
+
+.. code-block:: shell
+
+   rocprofv3 -E <path-to-extra_counters.yaml> --pmc <custom_metric> -- <app_relative_path>
+
 Kernel profiling output
 +++++++++++++++++++++++++