Delay invalid sdk_version error for AllowMissingDependencies

Unbundled builds set AllowMissingDependencies and attempt to use
prebuilts for some jars.  Delay the errors for missing jars for
modules with invalid sdk_version values in unbundled builds so
that they only block the build if those modules are built.

Also fix some error messages to show the original sdk_version
value.

Bug: 146513037
Test: m TARGET_BUILD_APPS=Camera2
Change-Id: I1812ef6dc80895f7a2162a8bdbf2c5067755e9a0