cmd/gomobile: rename bundleId to bundleID
cmd/gomobile: rename bundleId to bundleID

Renames the argument to the -bundleid command line flag to be
consistent with other parameter naming.

Change-Id: Icde0be0fbacb08712c415abce462070a84aa46d9
Reviewed-on: https://go-review.googlesource.com/79115
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/mobile,golang/mobile,golang/mobile,golang/mobile