## What changed?
<!-- Describe what has changed in this PR -->
Remove license header from every file. Because it is really hard to
follow in this PR here is the summary:
1. License header is removed from all `.go` and `.proto` files
:fireworks::fireworks:🎆.
2. `LICENSE` file in the root directory has only Temporal and Uber
copyrights.
3. 5 other `LICENSE` files added to the packages which have copyrights
different from Temporal and Uber: Datadog, Xargin, "Mat Ryer, Tyler
Bunnell and contributors".
4. `license_file` flag is removed from all code generation tools.
5. `copyright_file` flag is removed from `go:generate mockgen`
directive.
6. All copyright related targets are removed from `Makefile`.
7. Updated Temporal copyright year to 2025 everywhere.
## Why?
<!-- Tell your future self why have you made these changes -->
I double checked with legal department that it is not needed to have
license header in every file. One file per repo is enough. I put all
copyrights to the root `LICENSE` file and removed header from all other
files. Also updated tools and `Makefile`.
## What changed?
<!-- Describe what has changed in this PR -->
Remove dependency on grpc/example.
Add "testService" to support existing tests.
This will also be a good example on how to add server.
## Why?
<!-- Tell your future self why have you made these changes -->
We shouldn't depend on it to start with.
We run into problems with that dependency.
Latest version of grpc/examples depends on various aws libraries,
dependency I don't want to have.
## How did you test it?
<!-- How have you verified this change? Tested locally? Added a unit
test? Checked in staging env? -->
Existing tests.
## Potential risks
<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->
N/A
