Create a new certificate for 2021 CTS UICCs.

This certificate will be used to enforce a clean break between "old" CTS
UICCs and new ones. The new UICCs will have hardware support for new
calculations that the old ones aren't capable of.

Old certificate:
./testkey.x509.pem
SHA-1: 61:ED:37:7E:85:D3:86:A8:DF:EE:6B:86:4B:D8:5B:0B:FA:A5:AF:81
SHA-256: A4:0D:A8:0A:59:D1:70:CA:A9:50:CF:15:C1:8C:45:4D:47:A3:9B:26:98:9D:8B:64:0E:CD:74:5B:A7:1B:F5:DC

New certificate:
./cts_uicc_2021.x509.pem
SHA-1: 06:97:71:39:21:E8:65:D0:1C:45:C4:A8:8D:45:7A:9D:96:F4:39:27
SHA-256: CE:7B:2B:47:AE:2B:75:52:C8:F9:2C:C2:91:24:27:98:83:04:1F:B6:23:A5:F1:94:A8:2C:9B:F1:5D:49:2A:A0

We won't yet submit the change to switch the signature of
CtsCarrierApiTestCases, as that will introduce downstream presubmit and
postsubmit failures until the new hardware is available for device labs.

Bug: 178419755
Test: temporarily switch CtsCarrierApiTestCases to be signed with
cts-uicc-2021-testkey, ensure:
  - Suite fails on a device with the old CTS SIM due to lack of carrier
  privileges
  - Suite passes with updated cuttlefish modem simulator ARF content

Change-Id: I7598426bd3e4db90a8f0d8d80ea03468fb30f876