feat(metering): add metering for logs

[grandwizard28]

Features

• Add a pkg metering with interface metering.Meter for Size and Count usage calculation
• Add a pkg pdatagen for generating a wide variety of telemetry data for testing

[shivanshuraj1333]

=== RUN   TestLogsSize
    logs_test.go:24: 
        	Error Trace:	/Users/s/oss/sig/signoz-otel-collector/pkg/metering/v1/logs_test.go:24
        	Error:      	Not equal: 
        	            	expected: 3890
        	            	actual  : 3910
        	Test:       	TestLogsSize
--- FAIL: TestLogsSize (0.00s)

Expected :3890
Actual   :3910
<Click to see difference>


FAIL

Process finished with the exit code 1

[shivanshuraj1333]

We should have this package in the gateway-collector as I don't think it is going to be used in the signoz-collector

See, https://signoz-team.slack.com/archives/C050MERV57W/p1735396691630329?thread_ts=1735138328.325539&cid=C050MERV57W for more details.

[shivanshuraj1333]

This is redundant and not being use anywhere in the code.

[shivanshuraj1333]

this is hardcoded for json, in the gateway, through the encoder one can also configure proto, https://github.com/SigNoz/opentelemetry-gateway/blob/main/internal/processor/signozlimiterprocessor/processor.go#L91