wifi: rtw89: implement channel switch support

To support channel switch on STA mode, declare IEEE80211_HW_CHANCTX_STA_CSA
and implement ieee80211_ops::switch_vif_chanctx. Handling of CSA procedure
still relies on mac80211 SW flow, since FW doesn't support chanctx offload.
To support channel switch on AP mode, declare WIPHY_FLAG_HAS_CHANNEL_SWITCH
and implement ieee80211_ops::channel_switch_beacon additionally.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250605114207.12381-4-pkshih@realtek.com