fix(amazon q): add pl/1, bms filetypes #6067

## Problem
The codefileExtensions does not contain an extension type for `.pli`
which is the common extension for PL/1, or for `.bms` which is Basic
Mapping Support and common for screen definition files in IBM mainframe.
Because of this, the files and code in them are not accessible in the
workspace context for Amazon Q using the `/dev` quick action.

When using the Q quick action '\dev' for `.pli` or `.bms` files, Q
responds with the following message:
> This appears to be an empty program or workspace with no source files
present. There is nothing to explain at this time since no code or files
are available for analysis.

## Solution
- Add `.pli` and `.bms` as a known code file extension types.

packages/amazonq/.changes/next-release/Bug Fix-80f16b7a-440d-4e06-89ad-1454c58ff28f.json

@@ -0,0 +1,4 @@
+{
+	"type": "Feature",
+	"description": "Q feature dev: recognize .bms, .pli code files"
+}

packages/core/src/shared/filetypes.ts

@@ -161,6 +161,7 @@ export const codefileExtensions = new Set([
     '.bash',
     '.bat',
     '.boo',
+    '.bms',
     '.c',
     '.cbl',
     '.cc',
@@ -267,6 +268,7 @@ export const codefileExtensions = new Set([
     '.pike',
     '.pir',
     '.pl',
+    '.pli',
     '.pm',
     '.pmod',
     '.pp',