Revised native conda locator (#23416)

**Fixes**
* #23413
* & the fact that we always use the same conda exe to manage all conda
envs, even if multiple are installed.

* Step 1:
* Look for conda install folders in known locations such as `/<user
home>/miniconda3`, `<user profile>/Anaconda3`
* Step 2:
* For each install location identified, inspect that folder and extract
the
        * Conda executable
        * All environments belonging to that conda installation
* Step 3:
    * Old approach, 
* 1. find any conda in sys path or other locations and find conda
installation via that mechanism
* 2. Get all envs from environments.txt file (any remaining conda envs
not discovered in 1 & 2 will be discoverred here and use some the global
conda exe)
Once we have step 1 and 2, I do not expect anything new to show up in
step 3,
Even if users install conda into some custom locations (the solution
would be to run step 1 with the custom location provided by user in
settings.json file)

**How to find environments?**
* Look in the `envs` folder of the conda installation
* Look at the entries in the `environments.txt` file
* Look at the `env_dirs` in the `.condarc` file

With these two, we should be able to eliminate the need to ever spawn
conda to get the env directories.


**How do we know whether a conda environment belongs to a specific conda
installation**
* If it is in the `envs` sub directory of the conda installation
* Else, have a look at `<env folder>/conda-meta/history` file to look at
the conda installation that was used to create this environment

Author: DonJayamanne

native_locator/src/common_python.rs

@@ -50,7 +50,7 @@ impl Locator for PythonOnPath<'_> {
         })
     }
 
-    fn find(&self) -> Option<LocatorResult> {
+    fn find(&mut self) -> Option<LocatorResult> {
         let paths = self.environment.get_env_var("PATH".to_string())?;
         let bin = if cfg!(windows) {
             "python.exe"