[Build] Modify version info injection to fix sourcemaps (#1708)

* [Build] Preserve comments instead of adding header

...to avoid disrupting sourcemaps. Fixes #1707

[Build] Remove extraneous horizontal rule from header

[Build] Remove obsolete header-handling

...as this is handled by the replace task after fix for #1707

[Build] Move version headers into start.frag

...so that UMD boilerplate does not wrap it.

[Build] Handle version info entirely in start.frag

[Build] Replace build variables in start.frag explicitly

[Build] Inject build info dynamically

[Build] Test MCT.specifyBuildInfo

[Build] Mark BUILD_CONSTANTS as global for jshint

[Build] Give names to version line items

[Build] Fix specifyBuildInfo test case

* [Build] Update fix to sourcemaps for code review feedback

https://github.com/nasa/openmct/pull/1708

[Build] Move build info registration to plugin

https://github.com/nasa/openmct/pull/1708#discussion_r138999027

[Build] Use build info plugin

...instead of specifyBuildInfo

[Build] Revert changes to MCT, per code review

platform/core/bundle.js

@@ -94,31 +94,6 @@ define([
             }
         },
         "extensions": {
-            "versions": [
-                {
-                    "name": "Version",
-                    "value": "@@version",
-                    "priority": 999
-                },
-                {
-                    "name": "Built",
-                    "value": "@@timestamp",
-                    "description": "The date on which this version of the client was built.",
-                    "priority": 990
-                },
-                {
-                    "name": "Revision",
-                    "value": "@@revision",
-                    "description": "A unique revision identifier for the client sources.",
-                    "priority": 995
-                },
-                {
-                    "name": "Branch",
-                    "value": "@@branch",
-                    "description": "The name of the branch that was used during the build.",
-                    "priority": 994
-                }
-            ],
             "components": [
                 {
                     "provides": "objectService",