Link and Resource attribute count limits don't work

[owais]

Describe your environment

Current implementation does not respect link and resource (span) attribute limits.

Steps to reproduce

from opentelemetry import trace
from opentelemetry.sdk.trace import Resource, TracerProvider, SpanLimits
from opentelemetry.sdk.trace.export import (
    SimpleSpanProcessor,
    ConsoleSpanExporter,
)

attributes = {"k1": "v1", "k2": "v2"}

provider = TracerProvider(
    resource=Resource.create(attributes=attributes.copy()),
    span_limits=SpanLimits(max_attributes=1, max_link_attributes=1),
)
processor = SimpleSpanProcessor(ConsoleSpanExporter())
provider.add_span_processor(processor)
trace.set_tracer_provider(provider)


tracer = trace.get_tracer(__name__)

link = trace.Link(
    context=trace.INVALID_SPAN.get_span_context(), attributes=attributes.copy()
)

with tracer.start_as_current_span("s1", links=[link], attributes=attributes.copy()):
    pass

Run it:

❯ python main.py
{
    "name": "s1",
    "context": {
        "trace_id": "0xc20060d23fb374cc0e9441de3cf643b4",
        "span_id": "0xddddbe3ecde87eff",
        "trace_state": "[]"
    },
    "kind": "SpanKind.INTERNAL",
    "parent_id": null,
    "start_time": "2021-08-17T09:11:56.024238Z",
    "end_time": "2021-08-17T09:11:56.024257Z",
    "status": {
        "status_code": "UNSET"
    },
    "attributes": {
        "k3": "v3"
    },
    "events": [],
    "links": [
        {
            "context": {
                "trace_id": "0x00000000000000000000000000000000",
                "span_id": "0x0000000000000000",
                "trace_state": "[]"
            },
            "attributes": {
                "k1": "v1",
                "k2": "v2",
                "k3": "v3"
            }
        }
    ],
    "resource": {
        "telemetry.sdk.language": "python",
        "telemetry.sdk.name": "opentelemetry",
        "telemetry.sdk.version": "1.4.1",
        "k1": "v1",
        "k2": "v2",
        "k3": "v3",
        "service.name": "unknown_service"
    }
}

What is the expected behavior?
Resource and Link should have a single attribute just like the span.

What is the actual behavior?
Attribute count limits are not respected for resource and links as both of them contain more attributes than the limit (1).