Logstash - Plugins - SSL Settings Standardization - Standardize Elasticsearch FILTER settings

[edmocosta]

This issue should make the plugin SSL settings consistent with the naming convention defined in the meta issue. Missing settings already supported by the plugin's HTTP/TCP client, which only requires small coding changes on the plugin source, should also be added through this issue.

Add and deprecate options to comply with the naming convention

• ssl -> ssl_enabled
• ca_file -> ssl_certificate_authorities
• keystore -> ssl_keystore_path
• keystore_password -> ssl_keystore_password
• ca_trusted_fingerprint (specific for ES plugins)

Add common settings validations

• Not allow mixing the same deprecated and new setting on the same plugin configuration, e.g. ssl and ssl_enabled

Add missing settings/functionality that fits into the phase 1 description, and move non-phase 1-2 to the phase 3 issue (to be created if doesn't exist)

• ssl_certificate
• ssl_cipher_suites
• ssl_handshake_timeout (probably unsupported by ES client)
• ssl_key
• ssl_key_passphrase
• ssl_supported_protocols
• ssl_verification_mode
• ssl_keystore_type
• ssl_keystore_key_password
• ssl_truststore_path
• ssl_truststore_password
• ssl_truststore_type