deprecate default methods to read specific database credentials (#92)

The interface has some methods to read database credentials from
specific mountpoints like "mysql". While ann database mounts share
the same credential endpoints, the mount point itself can have any
name. Let's clean up some methods of low benefit and deprecate the
convenience methods.

Trivial replacement is `getDbCredentials()` with explicit mount point,
if it's actually mounted on that path.

Author: stklcode

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## unreleased
 
+### Deprecations
+* `read...Credentials()` methods for specific database mounts (#92)
+
 ### Dependencies
 * Updated Jackson to 2.18.3 (#90)
 

src/main/java/de/stklcode/jvault/connector/VaultConnector.java

@@ -681,7 +681,9 @@ default boolean createOrUpdateTokenRole(final TokenRole role) throws VaultConnec
      * @return the credentials response
      * @throws VaultConnectorException on error
      * @since 0.5.0
+     * @deprecated use {@link #readDbCredentials(String, String)} your MySQL mountpoint
      */
+    @Deprecated(since = "1.5.0", forRemoval = true)
     default CredentialsResponse readMySqlCredentials(final String role) throws VaultConnectorException {
         return readDbCredentials(role, "mysql");
     }
@@ -693,7 +695,9 @@ default CredentialsResponse readMySqlCredentials(final String role) throws Vault
      * @return the credentials response
      * @throws VaultConnectorException on error
      * @since 0.5.0
+     * @deprecated use {@link #readDbCredentials(String, String)} your PostgreSQL mountpoint
      */
+    @Deprecated(since = "1.5.0", forRemoval = true)
     default CredentialsResponse readPostgreSqlCredentials(final String role) throws VaultConnectorException {
         return readDbCredentials(role, "postgresql");
     }
@@ -705,28 +709,32 @@ default CredentialsResponse readPostgreSqlCredentials(final String role) throws
      * @return the credentials response
      * @throws VaultConnectorException on error
      * @since 0.5.0
+     * @deprecated use {@link #readDbCredentials(String, String)} your MSSQL mountpoint
      */
+    @Deprecated(since = "1.5.0", forRemoval = true)
     default CredentialsResponse readMsSqlCredentials(final String role) throws VaultConnectorException {
         return readDbCredentials(role, "mssql");
     }
 
     /**
-     * Read credentials for MSSQL backend at default mount point.
+     * Read credentials for MongoDB backend at default mount point.
      *
      * @param role the role name
      * @return the credentials response
      * @throws VaultConnectorException on error
      * @since 0.5.0
+     * @deprecated use {@link #readDbCredentials(String, String)} your MongoDB mountpoint
      */
+    @Deprecated(since = "1.5.0", forRemoval = true)
     default CredentialsResponse readMongoDbCredentials(final String role) throws VaultConnectorException {
         return readDbCredentials(role, "mongodb");
     }
 
     /**
-     * Read credentials for SQL backends.
+     * Read credentials for database backends.
      *
      * @param role  the role name
-     * @param mount mount point of the SQL backend
+     * @param mount mount point of the database backend
      * @return the credentials response
      * @throws VaultConnectorException on error
      * @since 0.5.0