cui: Use appropriate OUString functions on string constants

Change-Id: I3140945b57decf8ea605c35b11e18d063a5a5c83
chart2: Use appropriate OUString functions on string constants

Change-Id: Ia5a340049f787d7173140482853730a00d5d12df
dbaccess: Use appropriate OUString functions on string constants

Change-Id: Iea28ad5e1a469830e002471517197365fd6de3ee
filter: Use appropriate OUString functions on string constants

Change-Id: I4b1c365bb2ff80b30748630d2c6296bf4ed6fd53
forms: Use appropriate OUString functions on string constants

Change-Id: I196e847e2f63d1bac6ed0f520cba67508aec1a5d