feat(mcp): build flagset from mcp input schema to parse args

[burmudar]

We build a flagset from the input schema. This allows the input schema to be the
source of truth of the flags on the mcp command and ensures we are up to date with
the schema stored in the repository.

Part of SRCH-2167

Test plan

Added a test case and also executed locally with commit-search

[burmudar]

This change is part of the following stack:

• feat(mcp): add script to dump mcp tool list #1211
  • feat(mcp): parse mcp tool json #1212
    • feat(mcp): add mcp list-tools to list available tool calls #1213
      • feat(mcp): build flagset from mcp input schema to parse args #1215 ◀
        • feat(mcp): do mcp tool call from cli args #1216

_{Change managed by git-spice.}