Release Automation: Create a script to increment version numbers

[roberthbailey]

Is your feature request related to a problem? Please describe.
Right now there are a number of steps in the release process to increment version numbers in the install files, sdks, etc:

• Ensure the [helm tag value][values] is correct (should be {version} if a full release, {version}-rc if release candidate)
• Ensure the [helm Chart version values][chart] are correct (should be {version} if a full release, {version}-rc if release candidate)
• Update SDK Package Versions
  • Update the package version in [sdks/nodejs/package.json][package.json] and [sdks/nodejs/package-lock.json][package-lock.json] by running npm version {version} if a full release or npm version {version}-rc if release candidate
  • Ensure the [sdks/csharp/sdk/AgonesSDK.nuspec and sdks/csharp/sdk/csharp-sdk.csproj][csharp] versions are correct (should be {version} if a full release, {version}-rc if release candidate)
  • Update the package version in the [sdks/unity/package.json][unity] package file's Version field to {version} if a full release, {version}-rc if release candidate
• Run make gen-install
• If full release, then increment the base_version in [build/Makefile][build-makefile]
• If full release move [helm tag value][values] is set to {version}+1-dev
• If full release move the [helm Chart version values][chart] is to {version}+1-dev
• If full release, change to the sdks/nodejs directory and run the command npm version {version}+1-dev to update the package version
• If full release move the [sdks/csharp/sdk/AgonesSDK.nuspec and sdks/csharp/sdk/csharp-sdk.csproj][csharp] to {version}+1-dev
• If full release update the [sdks/unity/package.json][unity] package file's Version field to {version}+1-dev

Describe the solution you'd like
Create a script to bump the version numbers. Consider creating a target in the Makefile to execute the script.

[roberthbailey]

For the npm updates, we currently run the npm version command. We can continue to do this by executing npm inside of a docker container (so that we can control the npm version) or we can just use something like sed. We need to make sure that whatever solution we choose updates package-lock.json.