Improved display of Hooks/Custom Agents/Skills/MCP Servers/Instructions

**Problems**

There are a number of inconsistencies in how each of these are grouped/displayed
1. In some of them we have the folder name displayed, and not others
2. In some of them we have the file name dispalyed, and not others
3. The format for displaying folder/file names differ
4. Instructions have no notion of `Workspace` level instructions
I suppose this makes sense as its a whole different type of customization, however I'd expect Skills to follow this style as skills too can be loaded based on location/on demand
5. When adding MCP servers we cannot select the folder in which the MCP server is added (all others support this, Agents, Skills, Instructions, Hooks)
6. There's a `Workspace` group for Agents, Skills, Hooks, MCP Servers, but no group by folder name
7. Quick picks for creating skills/agents differ based on where its invoked from (sometimes we start with workspace folder and in others we start with the sub directory like .claude, .github, etc)
8. When we have a quick pick for creating skills/agents etc, the quick pick can be quite large and would be nice to group the locations based on worksapce folder, (we kind of already do this for user folder)

| | Folder Name Displayed | File Path Displayed |
| ------------- |:-------------:| -----:|
| Agents | No | No |
| Skills | No | No |
| Instructions | ✅ | ✅ |
| Hooks | ✅ | ✅ |
| MCP Servers | No | No |

### Agents

### Skills

### Create Skill Quickpick in Agents Window

### Create Skill Quickpick in Editor Window (Customization UI)

### Create Skill Quickpick in Editor Window (Command Palette)

## Instructions

### Create Instructions in Agents Window (Command Palette)

### Create Instructions in Editor Window (Customization UI)

### Create Instructions in Editor Window (Command Palette)

## Hooks

### MCP Servers