fix conversion of varchar to binary varbinary and vice versa

[tanscorpio7]

Description

Binary data type simply stores hex codes but when transformed to and from varchar, use of correct encoding becomes important. For example the symbol '™' is stored as
0xE284A2 in UTF-8 enc. while
0x99 in Win encoding
From users perspective they must see the hex value which is congruent to their server encoding.

To fix this we do necessary encoding to source data in varchar <--> varbinary internal functions.
Length checks should be done when data (hex string) is in server encoding.

We must also handle the case for string literal to binary types. So we explicitly call the varcharvarbinary conversion when a string literal is being casted to binary data type.

Also added CAST functions for sys.BBF_VARBINARY to sys.BBF_BINARY and vice versa
these cast are being used in geography and geometry cast functions
made necessary changes to geography and geometry casts as well
i.e. CAST (CAST ($1 AS sys.VARCHAR) AS sys.bbf_varbinary) --> CAST ($1 AS sys.bbf_varbinary)

Engine PR: babelfish-for-postgresql/postgresql_modified_for_babelfish#254

Extension PR: #2009

Issues Resolved

[BABEL-1940]

Sign-off

Signed-off-by: Tanzeel Khan [email protected]
Co-authored-by: Rohit Bhagat [email protected]

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