Publish-AzWebApp always cleans web app files, irrespective of -Clean option

### Description

Publish-AzWebApp has a Clean option, described as follows: Cleans the target directory prior to deploying the file(s).

However, when I run Publish-AzWebApp, it always cleans the /site/wwwroot on the web app (both files and directories). This irrespective of whether -Clean is used. Also irrespective of whether -TargetPath is used.

This makes it impossible to use Publish-AzWebApp to copy my web site to the web app using several calls to Publish-AzWebApp. This is critical, because 1) my web site has over 6GB of files; 2) our developers need to be able to update part of the site while leaving other parts alone.

It is treacherous too - if you use Publish-AzWebApp without -Clean, you can expect it to not clean /site/wwwroot, while it does without even an error message.

### Issue script & Debug output

```PowerShell
I ran the lines below in Powershell 7, and verified the outcome in the web app using an FTP client.
Not sure what you mean with a "debug stream"

# Set up the test. copies productionadmin to dir /site/wwwroot/k in the web app
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath productionadmin.zip -TargetPath k

# copies productionadmin to dir /site/wwwroot/y in the web app. k has been removed
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath productionadmin.zip -TargetPath y

# copies productionadmin to dir /site/wwwroot/x in the web app. y has been removed
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath productionadmin.zip -TargetPath x -Clean:$false

# copies productionadmin to dir /site/wwwroot/z in the web app. x has been removed
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath productionadmin.zip -TargetPath z -Clean:0

# runs without error messages. but sowadmin is not copied to the web app at all. z is still there
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath sowadmin.zip -TargetPath /site/wwwroot/b

# copies sowadmin to /site/wwwroot. but z has been removed
Publish-AzWebApp -ResourceGroupName $rg -Name $site -ArchivePath sowadmin.zip
```

### Environment data

```PowerShell
Name Value
---- -----
PSVersion 7.4.1
PSEdition Core
GitCommitId 7.4.1
OS Microsoft Windows 10.0.22621
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
```

### Module versions

```PowerShell
ModuleType Version PreRelease Name ExportedCommands
---------- ------- ---------- ---- ----------------
Script 2.15.1 Az.Accounts {Add-AzEnvironment, Clear-AzConfig, Clear-AzConte…
Script 3.2.0 Az.Websites {Add-AzWebAppAccessRestrictionRule, Add-AzWebAppT…
```

### Error output

```PowerShell
There is no error output. Publish-AzWebApp seems to work fine.
```

Start by reproducing the listed Publish-AzWebApp calls with different TargetPath and Clean values, then trace the Publish-AzWebApp implementation and its handling of those parameters. Done means deployments preserve existing /site/wwwroot content unless -Clean is explicitly enabled, while each specified target path receives its archive.

Written by the indexing model from the issue text.