GH-48119: [C++][ODBC] Move class definitions to type_fwd.h

[AestheticAkhmad]

Rationale for this change

This PR addresses the issue #48119

What changes are included in this PR?

Create type_fwd.h with forward declarations for ODBC classes to reduce compilation dependencies:

• Add new type_fwd.h with forward declarations for Statement, ResultSet, ResultSetMetadata, ODBCEnvironment, ODBCDescriptor, ODBCStatement, and ODBCConnection
• Replace full header includes with type_fwd.h
• Remove duplicate forward declarations from existing headers
• Update CMakeLists.txt to include new header

Are these changes tested?

No

Are there any user-facing changes?

No

• GitHub Issue: [C++][Flight SQL ODBC] Move class definitions to a type_fwd.h file #48119

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[github-actions]

⚠️ GitHub issue #48119 has been automatically assigned in GitHub to PR creator.

[github-actions]

⚠️ GitHub issue #48119 has been automatically assigned in GitHub to PR creator.

[lidavidm]

CC @alinaliBQ

[github-actions]

⚠️ GitHub issue #48119 has been automatically assigned in GitHub to PR creator.

[alinaliBQ]

@lidavidm Could you please help approving the CI workflows for this PR?