Use webpack to reduce the code loading times

[akshita31]

This PR enables the usage of webpack to bundle the extension, so that the corresponding js produced and the code load times are lesser, to fix issues like : #2817, #2757.

1. While working, we were facing problems that when webpack is used in production, the names of the classes were removed from the js files and hence the type checking we had in place for the logging pipeline(which was based on names of the classes) was falling apart, hence we have now modified the Observers to match based on enum values.
2. This will reduce the extension size to around 300Kb from current 3Mb 💃
3. Now in travis we dont need to unpack the extension we can run our tests against the dist folders directly, hence I have removed the gulp vsix:release:unpackage step and also the --codeExtensionPath flag being passed to the gulp tasks.

Also, this PR updates the vscode tasks to version 2.0.

[codecov]

Codecov Report

Merging #2835 into master will increase coverage by 21.28%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #2835       +/-   ##
===========================================
+ Coverage   64.87%   86.15%   +21.28%     
===========================================
  Files         104       58       -46     
  Lines        4501     1589     -2912     
  Branches      657      206      -451     
===========================================
- Hits         2920     1369     -1551     
+ Misses       1395      165     -1230     
+ Partials      186       55      -131

Flag	Coverage Δ
#integration	100% <ø> (+47.46%)	⬆️
#unit	86.15% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
src/NetworkSettings.ts	37.5% <0%> (-62.5%)	⬇️
src/packageManager/proxy.ts	42.1% <0%> (-36.85%)	⬇️
src/observers/BaseLoggerObserver.ts	60% <0%> (-20%)	⬇️
src/common.ts	55.55% <0%> (-18.89%)	⬇️
src/packageManager/PackageError.ts	83.33% <0%> (-16.67%)	⬇️
src/packageManager/ZipInstaller.ts	72.97% <0%> (-16.22%)	⬇️
src/platform.ts	60.22% <0%> (-15.91%)	⬇️
src/observers/OptionProvider.ts	57.14% <0%> (-14.29%)	⬇️
src/observables/CreateOptionStream.ts	88.88% <0%> (-11.12%)	⬇️
src/Disposable.ts	77.77% <0%> (-11.12%)	⬇️
... and 63 more

---

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[codecov]

Codecov Report

Merging #2835 into master will increase coverage by 22.3%.
The diff coverage is 98.83%.

@@            Coverage Diff             @@
##           master    #2835      +/-   ##
==========================================
+ Coverage   64.87%   87.17%   +22.3%     
==========================================
  Files         104       59      -45     
  Lines        4501     1739    -2762     
  Branches      657      206     -451     
==========================================
- Hits         2920     1516    -1404     
+ Misses       1395      168    -1227     
+ Partials      186       55     -131

Flag	Coverage Δ
#integration	100% <ø> (+47.46%)	⬆️
#unit	87.17% <98.83%> (+1.02%)	⬆️

Impacted Files	Coverage Δ
src/observers/ProjectStatusBarObserver.ts	100% <100%> (ø)	⬆️
src/observers/DotnetLoggerObserver.ts	100% <100%> (ø)	⬆️
src/observers/OmnisharpStatusBarObserver.ts	100% <100%> (ø)	⬆️
src/observers/TelemetryObserver.ts	92.3% <100%> (-7.7%)	⬇️
src/observers/DotnetChannelObserver.ts	100% <100%> (ø)	⬆️
src/observers/OmnisharpDebugModeLoggerObserver.ts	87.23% <100%> (-2.13%)	⬇️
src/observers/OmnisharpChannelObserver.ts	100% <100%> (ø)	⬆️
src/observers/ErrorMessageObserver.ts	100% <100%> (ø)	⬆️
src/observers/RazorLoggerObserver.ts	100% <100%> (ø)	⬆️
src/observers/DotnetTestLoggerObserver.ts	98.61% <100%> (-1.39%)	⬇️
... and 84 more

---

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[colombod]

Looks good to me, great job in size reduction.

[rchande]

Nice work--thanks!

[akshita31]

Through this work we were able to reduce the code load time from ~430 ms to 40ms.
This is a screenshot for the activation time of the extension for a simple workspace for extension version 1.17

And here is the same for the 1.18-beta7