Update to Proxystore v0.5.0

[gpauloski]

This PR updates Colmena to use ProxyStore v0.5.0. The synthetic-data demo app is also updated.

Here's the changes to colmena/ (i.e., ignoring the demo app and doc changes):

1. The Store now has .config() and .from_config() methods. This greatly simplifies the storing the ProxyStore configuration within each Result object and recreating the Store if necessary when serializing the Result.
2. The tests which use ProxyStore needed to be updated to use the new Connector model (a straightforward change).
3. The format of data returned by store_proxy_stats (which is stored in Result) has changed. While the data is more informative/human-readable, this is a breaking change for any code that parses Result.proxy_timing. An example can be found here, and a sample entry in Result.proxy_timing is provided below.

>>> result.proxy_timing
{
    "FileKey(filename='7f4e12ba-622f-4946-ac01-9e3e5fee879d')": {
        "attributes": {"store.get.object_size": 1000165},
        "counters": {"store.get.cache_misses": 1},
        "times": {
            "store.get.connector": {
                "count": 1,
                "avg_time_ms": 189.037,
                "min_time_ms": 189.037,
                "max_time_ms": 189.037,
                "last_time_ms": 189.037,
                "last_timestamp": 1683940464.067098,
            },
            "store.get.deserialize": {
                "count": 1,
                "avg_time_ms": 427.167,
                "min_time_ms": 427.167,
                "max_time_ms": 427.167,
                "last_time_ms": 427.167,
                "last_timestamp": 1683940464.0675457,
            },
            "store.get": {
                "count": 1,
                "avg_time_ms": 689.462,
                "min_time_ms": 689.462,
                "max_time_ms": 689.462,
                "last_time_ms": 689.462,
                "last_timestamp": 1683940464.0675554,
            },
            "factory.resolve": {
                "count": 1,
                "avg_time_ms": 708.168,
                "min_time_ms": 708.168,
                "max_time_ms": 708.168,
                "last_time_ms": 708.168,
                "last_timestamp": 1683940464.0675676,
            },
            "factory.call": {
                "count": 1,
                "avg_time_ms": 768.181,
                "min_time_ms": 768.181,
                "max_time_ms": 768.181,
                "last_time_ms": 768.181,
                "last_timestamp": 1683940464.067604,
            },
        },
    },
}

[WardLT]

LGTM minus a suggested edit in the docs. Thanks, @gpauloski !