[receiver/postgresql] add basic query sample collection for postgresqlreceiver (open-telemetry#39573)

#### Description
we introduced the top query collection to postgresql receiver. this will
collect the queries from `pg_stat_statements` and report the related
metrics. this will help the end user to identify which queries are most
executed, and resources most used.

Example output:
```
resourceLogs:
  - resource:
      attributes: []
    scopeLogs:
      - logRecords:
          - attributes:
              - key: db.system.name
                value:
                  stringValue: postgresql
              - key: db.namespace
                value:
                  stringValue: postgres
              - key: db.query.text
                value:
                  stringValue: "select * from pg_stat_activity where id = ?"
              - key: postgresql.calls
                value:
                  intValue: 3
              - key: postgresql.rows
                value:
                  intValue: 10
              - key: postgresql.shared_blks_dirtied
                value:
                  intValue: 1
              - key: postgresql.shared_blks_hit
                value:
                  intValue: 2
              - key: postgresql.shared_blks_read
                value:
                  intValue: 3
              - key: postgresql.shared_blks_written
                value:
                  intValue: 4
              - key: postgresql.temp_blks_read
                value:
                  intValue: 5
              - key: postgresql.temp_blks_written
                value:
                  intValue: 6
              - key: postgresql.queryid
                value:
                  stringValue: "114514"
              - key: postgresql.rolname
                value:
                  stringValue: master
              - key: postgresql.total_exec_time
                value:
                  doubleValue: 1
              - key: postgresql.total_plan_time
                value:
                  doubleValue: 1
            body:
              stringValue: top query
        scope:
          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/postgresqlreceiver
          version: 0.0.1
```

Author: cuichenli

.chloggen/postgresql-add-top-query-collection.yaml

@@ -0,0 +1,27 @@
+# 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: postgresqlreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: we introduced the top query collection to postgresql receiver. this will collect the queries from `pg_stat_statements` and report the related metrics. this will help the end user to identify which queries are most executed, and resources most used.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39573]
+
+# (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]