Fail server startup when opening TLS context fails #26065
Description
Enhancement
Related to #24141
When specifying non-existent files for ssl-cert and/or ssl-key this happens:
[2021/07/08 17:11:43.194 +02:00] [WARN] [misc.go:445] ["load x509 failed"] [error="open /home/dvaneeden/tls/cert-nonexistend.pem: no such file or directory"]
[2021/07/08 17:11:43.194 +02:00] [ERROR] [server.go:198] ["secure connection cert/key/ca load fail"] [error="open /home/dvaneeden/tls/cert-nonexistend.pem: no such file or directory"]
[2021/07/08 17:11:43.194 +02:00] [INFO] [server.go:224] ["server is running MySQL protocol"] [addr=0.0.0.0:4000]
Note that startup already fails if -require-secure-transport is used with invalid certificate paths.