[TIMOB-7965] iOS WebView: handle titanium injections for local files via customized protocol handler

The refactored approach loads file:// URLs via customized protocol handler that performs titanium injections.

Two nice side effects:
1. WebView now could reference compiled JS files. (reduces builder.py/CLI logic to track these files in html)
2. Before the fix, only the first local page did get titanium injection. With the fix, any local page gets it.

Resolves tickets:
[TIMOB-7965](https://jira.appcelerator.org/browse/TIMOB-7965)
[TIMOB-4474](https://jira.appcelerator.org/browse/TIMOB-4474)
[TIMOB-11983](https://jira.appcelerator.org/browse/TIMOB-11983)
[TIMOB-9461](https://jira.appcelerator.org/browse/TIMOB-9461)

Functional testing:
1. Regression testing with KS: all Views/WebView tests
2. [TIMOB-7965](https://jira.appcelerator.org/browse/TIMOB-7965)
3. [TIMOB-11983](https://jira.appcelerator.org/browse/TIMOB-11983)
4. [TIMOB-9461](https://jira.appcelerator.org/browse/TIMOB-9461)