[NET-6741] make: Add target for updating dependencies across all modules

[zalimeni]

To enable more consistent and error-proof dependency management, add a Make target that will set a dependency version across all submodules that require it.

Replicates hashicorp/consul#19785 in consul-dataplane.

This really just ensures the main go.mod stays in sync w/ int tests for now, but could help more in the future.

How I've tested this PR

Example run:

❯ make go-mod-get DEP_VERSION=github.com/hashicorp/go-hclog@v1.5.0
--> Running go get github.com/hashicorp/go-hclog@v1.5.0 (.)
go: upgraded github.com/hashicorp/go-hclog v1.2.2 => v1.5.0
--> Running go mod tidy (.)
--> Running go get github.com/hashicorp/go-hclog@v1.5.0 (./integration-tests)
go: upgraded github.com/hashicorp/go-hclog v1.2.2 => v1.5.0
--> Running go mod tidy (./integration-tests)

❯ git status
On branch zalimeni/net-6741-add-make-target-dependency-update-modules
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   go.mod
	modified:   go.sum
	modified:   integration-tests/go.mod
	modified:   integration-tests/go.sum