Added two new metrics for vcenter receiver (#37253)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
This PR adds the vcenter.vm.memory.granted and vcenter.host.cpu.capacity
metric.
More information on this metric can be found
[here](https://docs.vmware.com/en/vRealize-Operations/8.10/com.vmware.vcom.metrics.doc/GUID-41603CD6-453B-4E26-A237-34E733BAB00C.html).

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#37257 


<!--Describe what testing was performed and which tests were added.-->
#### Testing
The metric was scraped from a test vCenter environment, and golden test
files were updated to reflect the addition of the metric.


<!--Describe the documentation added.-->
#### Documentation
Documentation was updated according to the metadata.yaml


<!--Please delete paragraphs that you did not use before submitting.-->

<img width="959" alt="Screenshot 2025-01-14 at 10 48 02 AM"
src="https://github.com/user-attachments/assets/7c88902f-fe21-4c7d-be17-ba79a92222f3"
/>

<img width="919" alt="Screenshot 2025-01-15 at 11 35 31 AM"
src="https://github.com/user-attachments/assets/77e19e19-93e4-410a-b501-6477c77e78da"
/>

Co-authored-by: Antoine Toulme <[email protected]>

.chloggen/add-two-new-vecenter-receiver-metrics.yaml

@@ -0,0 +1,21 @@
+# Use this changelog template to create an entry for release notes.
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: vcenterreceiver
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds vCenter memory capacity for hosts and memory granted metric for VMs." 
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues:  [37257]
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/vcenterreceiver/documentation.md

@@ -802,6 +802,32 @@ The vSAN throughput of a virtual machine.
 | ---- | ----------- | ------ |
 | direction | The type of vSAN throughput. | Str: ``read``, ``write`` |
 
+## Optional Metrics
+
+The following metrics are not emitted by default. Each of them can be enabled by applying the following configuration:
+
+```yaml
+metrics:
+  <metric_name>:
+    enabled: true
+```
+
+### vcenter.host.memory.capacity
+
+Total memory  capacity of the host system.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| MiBy | Sum | Double | Cumulative | false |
+
+### vcenter.vm.memory.granted
+
+The amount of memory that is granted to a VM.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| MiBy | Sum | Int | Cumulative | false |
+
 ## Resource Attributes
 
 | Name | Description | Values | Enabled |