Missing `db*()` implementations

[Jarod G.R. Meng]

The following DBI db() implementations are currently missing from RPresto:

• dbGetRowsAffected()
• dbExecute()
• dbCreateTable()
• dbAppendTable()
• dbWriteTable()
• dbRemoveTable()
• dbBind()

[Jarod G.R. Meng]

#157 implemented the following:

• dbGetRowsAffected() and get dbExecute() for free
• dbCreateTable()
• dbRemoveTable()

The remaining are currently difficult to implement given how the code is written:

• dbBind()
• dbAppendTable()
• dbWriteTable()

[Jarod G.R. Meng]

#161 implements a simple dbWriteTable().

The remaining db*() methods yet to be implemented:

• dbBind()
• dbAppendTable()

[Jarod G.R. Meng]

#211 added dbAppendTable() support.

[Jarod G.R. Meng]

Closing this issue for now as we're not adding dbBind() implementation for now.