Respect transport parameters and allowed net types (#901)

## Summary

This change makes transport/network-type handling consistent across
candidate gathering and remote candidate admission.

It fixes cases where the ICE agent could use STUN/TURN URLs with
mismatched transport or accept remote candidates on disabled network
types.

## What changed

### 1) Remote candidate filtering by configured network types

- Added a guard in `addRemoteCandidate` to ignore candidates whose
`NetworkType` is not enabled in `AgentConfig.NetworkTypes`.
- Added logging for ignored candidates.

### 2) URL transport interpretation and filtering

- Added helpers:
- `effectiveURLProtoType` (applies default transport when URI transport
is omitted)
  - `urlSupportsSrflxGathering`
  - `relayNetworkTypesForURL`
  - `configuredNetworkTypes`
- Applied this logic to srflx gathering (`gatherCandidatesSrflx`,
`gatherCandidatesSrflxUDPMux`) so only valid UDP URLs are used.

### 3) Relay gathering honors network types and filtered local binds

- Refactored relay gathering to select per-URL/per-network-type behavior
instead of hardcoded network assumptions.
- Kept support for interface/IP filtered local binding addresses in
relay/srflx paths.
- Replaced manual host:port formatting in srflx paths with
`net.JoinHostPort(..., strconv.Itoa(...))` for safer address
construction.

### 4) IPv6 TURN status (important)

- IPv6 TURN code paths were updated and covered by tests, but full IPv6
TURN support is not complete yet.
- For now, IPv6 TURN relay gathering is intentionally disabled in
runtime path.
- Related IPv6 relay test scenario is present but currently skipped
(`t.Skip("IPv6 TURN is not supported yet")`).

### Reference issue
Fixes #367

Use semver format for go version

Improve active_tcp test timeout

Deprecate AgentConfig

Cancel gathering before removing candidates (#842)

#### Description

When ICE agent is closed, the connections from UDP/TCP mux were removed
before gathering was canceled. This led to candidate gathering adding
entries to UDP mux which were not cleaned up.

~Also passing into logger to the mux as ICE agent logger could have more
context and is useful to see the context.~

Set linger time for tcp connections (#841)

#### Description

It is possible that Close() of a TCP connection to block if there is
pending data to be written till it is written out. Set linger to ensure
that it does not block.

Fix a deadlock in TaskLoop

Implement ICE Role conflict resolution

Detect if remote has a role conflict and resolve it as defined by
RFC 8445 section-7.3.1.1

Resolves #359

Pass LoggerFactory to dtls and mdns (#772)

Handle candidate: prefix with UnmarshalCandidate

Make UnmarshalCandidate able to handle candidate: prefix in the
candidate string.