Avoid caching packages

[DonJayamanne]

I think this should be avoided, as it is this is causing a few issues in Jupyter.
E.g. i can uninstall/install packages from Jupyter extension by running code like %pip install in a cell
This is valid jupyter code, and very commonly used practice.

However the Python env tools returns stale information, hence the Python tools used in Copilot return stale information.
Restarting Jupyter kernels. or restarting the chat doesn't fix the issue, I need to reload VS Code.

Not sure why we need the cache, but i think its fair to say that we've learnt that caching can cause a lot of issues.

    async getPackages(environment: PythonEnvironment): Promise<Package[] | undefined> {
        if (!this.packages.has(environment.envId.id)) {
            await this.refresh(environment);
        }
        return this.packages.get(environment.envId.id);
    }

[karthiknadig]

We should monitor and refresh the packages whenever we see a Python package folder get added to site-packages. Depending on the scenario. There can be lots of calls to get package list, and we don’t want it to run pip or conda every single time.