[vim/vim] vim9: E1001 compiling a lambda nested in a :def that references a script variable declared in an enclosing block — compile_lambda() does not inherit uf_blo ck_ids (Issue #20876)

neoharju created an issue (vim/vim#20876)

### Steps to reproduce

```vim9script
vim9script
if 1
    const c = 42
    def F(): number
        var G = () => c
        return G()
   enddef
   defcompile
endif
```

→ E1001: Variable not found: c 

### Expected behaviour

Two nearly identical cases compile fine, which is what makes this look like a bug rather than intended scoping: 
" 1. Same lambda, but the variable is at top-level script scope: OK
```vim9script
vim9script
const c = 42
def F(): number
    var G = () => c
    return G()
enddef
defcompile
```

" 2. Same block-scoped variable, referenced directly by the :def
" instead of through a nested lambda: OK
```vim9script
vim9script
if 1
    const c = 42
    def F(): number
         return c
    enddef
    defcompile
endif
```

So a :def can see a block-scoped script variable, and a lambda can see a top-level script variable, but a lambda nested inside that :def cannot
see the block-scoped one. 

### Version of Vim

Vim 9.2 (patches 1-804, commit 6f02e5cd7, --with-features=huge), Linux x86_64. 

### Environment

suggestion for fix [0002-vim9-lambda-inherit-block-ids.patch](https://github.com/user-attachments/files/30523569/0002-vim9-lambda-inherit-block-ids.patch)

### Logs and stack traces

```shell

```

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