test: subsys: jwt: fix testing of the features

- Some files (PEM/DER files, jwt-test-cert.c, user-tls-conf.h)
  were removed because they are not used or no longer necessary.
  Private keys used in the test are now in the jwt-test-private.c
  file as arrays.
- testcase.yaml has been improved in order to test all possible
  use cases: ECDSA with TC, ECDSA with PSA, RSA;
- unnecessary Kconfigs were removed from prj.conf.

Signed-off-by: Valerio Setti <[email protected]>

Author: valeriosetti

tests/subsys/jwt/jwt-test-cert.pem

@@ -2,21 +2,10 @@ CONFIG_BASE64=y
 CONFIG_JSON_LIBRARY=y
 CONFIG_JWT=y
 CONFIG_ZTEST=y
-# CONFIG_ZTEST_STACK_SIZE=2048
 CONFIG_ZTEST_STACK_SIZE=8192
 
 # Enable CSPRNG
 CONFIG_ENTROPY_GENERATOR=y
 CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR=y
 
-# Enable MBEDTLS
-CONFIG_MBEDTLS=y
-CONFIG_MBEDTLS_BUILTIN=y
-CONFIG_MBEDTLS_ENABLE_HEAP=y
-CONFIG_MBEDTLS_HEAP_SIZE=32700
-CONFIG_MBEDTLS_USER_CONFIG_ENABLE=y
-CONFIG_MBEDTLS_USER_CONFIG_FILE="user-tls-conf.h"
-
-CONFIG_NET_SOCKETS=y
-
 CONFIG_REQUIRES_FULL_LIBC=y