[TrilinosApplication] Minor clean-up

[loumalouomega]

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name: ✨ Feature
about: Minor clean-up and build fixes

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📝 Description

Small, targeted clean-ups and build-system fixes related to the Trilinos integration.

What changed

• Adjusted CMake in order to pure-proof TPetra compatibility (WIP).
• Prepare to compile benchmarks in TrilinosApplication.
• Clean up headers.

🆕 Changelog

• Add Tpetra definitions and benchmark sources to TrilinosApplication CMake
• Refactor TrilinosApplication header and source files