Add CPM & multiple package manager commands

[devlead]

This PR Fixes #9944

• Add tab to command palette for Central Package Management XML
• Support for copying individual package manager commands separately

Example dark theme

Example light theme

UI Comparison

Package Type	Package Manager	Current	Proposed
Standard	.NET Cli
Standard	Package Manager
Standard	PackageReference
Standard	CPM	N/A
Standard	Paket CLI
Standard	Script & Interactive
Standard	Cake
SDK	SDK
.NET Tool	.NET CLI (Global)
.NET Tool	.NET CLI (Local)
.NET Tool	Cake
.NET Tool	Nuke
.NET Template	.NET Cli
Cake Addin	Cake
Cake Module	Cake
Cake Recipe	Cake

[erdembayar]

@OliaG
Could you please take a look at proposed UI change?
Only concern I have is "Central package management" is quite long term compare to other tabs, we're running out of real estate space on that menu.

[zivkan]

Perhaps the CPM snippets could be put on the same tab as PackageReference. Prefix one with "if you're not using CPM", and the other with "If you are using CPM". After all, CPM still uses <PackageReference Include="

[OliaG]

I actually like the separate tab Central Package Management better as it is suggested originally, but I would capitalize the word "management" in the tab. Should be "Central Package Management"

[OliaG]

LGTM from the user experience, minor request - to capitalize "management" in the tab name.
I haven't reviewed the implementation details.