Allow ParseOptions to compose multiple option parsers easily

There are certain options which we need to share in multiple binaries,
for example, the signer options. Current options parsing function only
accepts 1 extra option handler, which is inflexible. Extend it to take a
list of extra option handlers.

Currently, to add a new CLI flag, caller must append the flag name to
`extra_long_opts`, then pass an extra option handler which can handle
that option. Define a new dataclass which contains both the CLI flag
name and the code to handle that flag for better composition.

Test: th
Bug: 293313353
Change-Id: I758db66dfd95934f5b2701454d97bfe7d37dc16d