[receiver/tls_check] rename to tls_check with deprecated alias tlscheck

[nicknikolakakis]

Part of:

• Rename components to match naming convention #45339

Description

Renames the tlscheck receiver type to tls_check to match the snake_case naming convention established in open-telemetry/opentelemetry-collector#14208.

The previous type tlscheck is preserved as a deprecated alias via xreceiver.WithDeprecatedTypeAlias, so existing user configurations remain functional and will log a deprecation warning at startup.

Metric names (tlscheck.*) and the directory layout (receiver/tlscheckreceiver) are intentionally unchanged to avoid user-facing breakage, matching the precedent set by other receiver renames under #45339.

Link to tracking issue

Part of #45339

Testing

• make generate regenerates all metadata files with the new type
• go test ./... passes
• make lint passes (via make generate which includes fmt + gci)
• make chlog-validate passes
• make gendistributions and make generate-chloggen-components produce matching diffs

Documentation

• Added deprecation note in README.md
• Updated the config example to use tls_check:

[otelbot]

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