Update release tooling to handle both stable and unstable crates (#3082)

## Motivation and Context
This PR updates our smithy-rs release tooling to prepare for handling
both stable and unstable crates. Merging this PR to `main` does not make
any of the runtime crates stable, instead we will just have a supporting
mechanism in place, ready to be turned on by implementing `TODO(GA)`.
 
## Description
At a high level, this PR will
- update the `Release smithy-rs` workflow UI to have an additional input
`Stable semantic version`:
![Screenshot 2023-10-24 at 10 19 07
PM](https://github.com/awslabs/smithy-rs/assets/15333866/097502e6-3193-43f6-b39b-dd231c2d14d7)
- split an existing gradle property `smithy.rs.runtime.crate.version`
into `smithy.rs.runtime.crate.stable.version` and
`smithy.rs.runtime.crate.unstable.version`.
- make `publisher upgrade-runtime-crates-version` take a new, optional
(for backwards compatibility) command line argument `--stable-version`
to use the said gradle property
`smithy.rs.runtime.crate.stable.version`. This will allow the
`publisher` to set a value passed via a workflow input `Stable semantic
version` to `smithy.rs.runtime.crate.stable.version` in
`gradle.properties` (and the same goes for unstable crates).
- update `fixRuntimeCrateVersions` so that it fixes up runtime crate
versions based on properties `smithy.rs.runtime.crate.stable.version`
and `smithy.rs.runtime.crate.unstable.version`.

**NOTE**
There is a guard in place. When this PR gets merged and then we enter a
stable crate version in the `Stable semantic version` text box, it will
be overwritten by a version in `Unstable semantic version`, so that
1.x.y version will NOT be published to `crates.io` before GA and that
also replicates today's release workflow's behavior (only publishing
unstable crates). Just make sure we specify a 0.x.y in the `Untable
semantic version` text box because that does get shipped.

### What happens once `TODO(GA)` has been implemented?
Roughly, it will look like this. When we run the `Release smithy-rs`
workflow (not a dry-run), providing a stable version (say 1.0.0) and a
unstable version (say 0.57.0) in the workflow text boxes,
1. the workflow will create a new release branch
`smithy-rs-release-1.x.y`.
2. the workflow will set 1.0.0 to
`smithy.rs.runtime.crate.stable.version` and 0.57.0 to
`smithy.rs.runtime.crate.unstable.version` in `gradle.properties`.
3. for whatever smithy runtime crates whose package metadata says
```
[package.metadata.smithy-rs-release-tooling]
stable = true
```
their `Cargo.toml` will include `version = 1.0.0` (and `version =
0.57.0` if `smithy-rs-release-tooling` is not specified or if its value
is `stable = false`).

4. the workflow will publish smithy runtime crates accordingly to
`crates.io`.
5. releasing `aws-sdk-rust` subsequently will render `version = 1.0.0`
in `Cargo.toml` for stable AWS runtime crates (again as specified by
`smithy-rs-release-tooling`), will render `version = 1.1.0` for SDK
crates (we will not go into details here as to why it's not `1.0.0`),
and will publish those crates to `crates.io`.
 
## Testing
In a [separate
branch](https://github.com/awslabs/smithy-rs/tree/ysaito/stable-and-unstable-crates

)
that implemented `TODO(GA)`, I verified that
- our internal release pipeline was executed without errors
- a generated AWS SDK had following manifests (showing excerpts from
arbitrary crates)
```
[package]
name = "aws-sdk-s3"
version = "1.1.0"
```
```
[package]
name = "aws-smithy-types"
version = "1.0.0"
```
```
[package]
name = "aws-smithy-http"
version = "0.57.0"
```
```
[package]
name = "aws-types"
version = "1.0.0"
```
```
[package]
name = "aws-config"
version = "1.0.0"
```
----
 
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choice._

---------

Co-authored-by: John DiSanti <jdisanti@amazon.com>