add support for BIGINT UNSIGNED <--> java.math.BigInteger

[tpetr]

This PR adds support for java.math.BigInteger to the Vitess JDBC driver:

• Add support for BigInteger parameters in VitessPreparedStatements
• Add an explicit getBigInteger() to VitessResultSet
• Update unit tests to flex BigInteger for both classes.

@harshit-gangal @acharis

[harshit-gangal]

Currently there are 3 way to use BigInteger.

setBigDecimal("mysql_bigIntCol", new BigDecimal("1234567890"))
setLong("mysql_bigIntCol", Long.parseLong("1234567890")) if value can fit within a long
setString("mysql_bigIntCol", "1234567890") to let the JDBC driver convert the string for you

Statement and PreparedStatement method does not allow any other way.

The method you have added will only be accessible if you type cast them into VitessStatement or VitessPreparedStatement.

Do you really need to add this or can you use the above way as workaround?

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Comments from Reviewable

[tpetr]

@harshit-gangal Apologies for the slow response. We need this because JDBI calls VitessPreparedStatement.setObject() to bind parameters when constructing a query. If one of the parameters is a BigInteger you currently get an exception like this:

java.sql.SQLException: Cannot infer the SQL type to use for an instance of java.math.BigInteger
	at io.vitess.jdbc.VitessPreparedStatement.setObject(VitessPreparedStatement.java:379)
	at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.setObject(HikariProxyPreparedStatement.java)
	at org.skife.jdbi.v2.ObjectArgument.apply(ObjectArgument.java:35)
	at org.skife.jdbi.v2.ColonPrefixNamedParamStatementRewriter$MyRewrittenStatement.bind(ColonPrefixNamedParamStatementRewriter.java:167)
	... 88 common frames omitted

[harshit-gangal]

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Reviewed 4 of 4 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[acharis]

LGTM