cleanup: fix typings for command/build_order.py

[shubhbapna]

part of #226

fixes

src/fromager/commands/build_order.py:15: error: Function is missing a return type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:15: note: Use "-> None" if function does not return a value
src/fromager/commands/build_order.py:28: error: Function is missing a return type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:71: error: Incompatible types in assignment (expression has type "TextIO | Any", variable has type "TextIOWrapper")  [assignment]
src/fromager/commands/build_order.py:92: error: Function is missing a return type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:102: error: Need type annotation for "dist_to_input_file"  [var-annotated]
src/fromager/commands/build_order.py:113: error: Incompatible types in assignment (expression has type "TextIO | Any", variable has type "TextIOWrapper")  [assignment]
src/fromager/commands/build_order.py:146: error: Function is missing a return type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:153: error: Function is missing a type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:160: error: Function is missing a type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:168: error: Function is missing a type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:169: error: Call to untyped function "new_node" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:178: error: Need type annotation for "nodes" (hint: "nodes: dict[<type>, <type>] = ...")  [var-annotated]
src/fromager/commands/build_order.py:186: error: Call to untyped function "update_node" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:187: error: Call to untyped function "fmt_req" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:200: error: Call to untyped function "update_node" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:200: error: Call to untyped function "fmt_req" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:201: error: Call to untyped function "update_node" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:201: error: Call to untyped function "fmt_req" in typed context  [no-untyped-call]
src/fromager/commands/build_order.py:213: error: Incompatible types in assignment (expression has type "TextIO | Any", variable has type "TextIOWrapper")  [assignment]
src/fromager/commands/build_order.py:282: error: Function is missing a return type annotation  [no-untyped-def]
src/fromager/commands/build_order.py:323: error: Function is missing a return type annotation  [no-untyped-def]