Optimize euicc invocations by keeping channel open session ends.

Original Design for back-to-back send()'s:

Lock -> Open -> Send APDU A1, A2, A3 -> Close -> Unlock
Lock -> Open -> Send APDU B1 -> Close -> Unlock
Lock -> Open -> Send APDU C1, C2 -> Close -> Unlock

New Design:

EuissSession start
Lock -> Open -> Send APDU A1, A2, A3 -> Unlock
Lock -> Send APDU B1 -> Unlock
Lock -> Send APDU C1, C2 -> Unlock
EuissSession end -> Lock -> Close -> Unlock

Flag: com.android.internal.telephony.flags.optimization_apdu_sender
Bug: 335257880
Test: unit test
Test: manual test b/335257880#comment11 - download eSIM w/ enable, download eSIM w/o enable, enable eSIM, disable eSIM, erase eSIM, p+e to e+e, e+e to p+e.
Test: QA result no regression b/335257880#comment15

Change-Id: Iba187a609539f187e4d34dc000297c7810b897e2