[FIRRTL] Need to handle Macro Collision

Nobody has claimed this yet.

If a FIRRTL name collides with a macro, the compiler currently crashes. `LowerToHW` and others need to disconnect the symbol creation from the name of the symbol. `sv.macro.decl` already has support for this. It is not used yet.

Consider:

```
FIRRTL version 4.0.0
circuit RANDOM:
module RANDOM:
input clock: Clock
input d: UInt<1>
output q: UInt<1>

reg r: UInt<1>, clock

connect r, d
connect q, r
```

This errors during `LowerToHW` with:

```
:0: error: Referenced macro doesn't exist "ENABLE_INITIAL_MEM_"
:0: note: see current operation: "sv.macro.def"() {format_string = "", macroName = @ENABLE_INITIAL_MEM_, symbols = []} : () -> ()
```

Start by reproducing the FIRRTL example and tracing the failure in LowerToHW. Read the existing sv.macro.decl support and the related symbol-creation paths; done when a FIRRTL name colliding with a macro no longer causes an invalid macro reference or compiler crash.

Written by the indexing model from the issue text.