register 'execute commands' onto Project Manager

[Eskibear]

Requires microsoft/vscode-java-dependency#311

[Eskibear]

Note that the wording "execute commands..." here might be not clear enough.
In Maven extension, the full name of the command (in command palette) is "Maven: execute commands...", because the group is "Maven".

[jdneo]

Will you consider change it to Execute Maven Commands...? IMO, trigger the command from Maven & Project explorer may be more frequency than in command palette.

[Eskibear]

Then the side effect would be "Maven: Execute Maven Commands..." in command palette. And yes it's OK for me.

[jdneo]

So now we have three possible solution per offline discussion:

• Change to Maven: Execute Maven Commands...
• Wrap another command for tree view usage
• Open a ticket to VS Code about adding a treeview display name for a command

[Eskibear]

Now using an alias command maven.goal.execute.fromProjectManager for the same functionality.