[Server] Implement gRPC handlers

[graysonguarino]

N/A

Issue Number:
Reference the issue this PR fixes.

Rework of #25

Description of Changes:
Provide a clear and concise explanation of what changes you made and why.

• Add gRPC handlers for Database service
• Add unit tests for handlers

Testing Done:
How did you test your changes? Share details like steps, tools used, or results.

• Initial unit tests added

Terms of contribution:

By submitting this pull request, I agree that this contribution is licensed under the terms of the Apache License, Version 2.0.

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[hallyn-geico]

Run cargo fmt --all -- --check
error: 'cargo-fmt' is not installed for the toolchain '1.87.0-x8[6](https://github.com/geico/tuxtape/actions/runs/15122951183/job/42509277217?pr=26#step:4:7)_64-unknown-linux-gnu'.
To install, run `rustup component add rustfmt`

[graysonguarino]

Run cargo fmt --all -- --check
error: 'cargo-fmt' is not installed for the toolchain '1.87.0-x8[6](https://github.com/geico/tuxtape/actions/runs/15122951183/job/42509277217?pr=26#step:4:7)_64-unknown-linux-gnu'.
To install, run `rustup component add rustfmt`

@ecpullen do you want to fix the action or do you want me to take a crack at it?