refactor: consolidate tiller addon spec

[jackfrancis]

Reason for Change:

Eases maintenance of the tiller addon by consolidating manifests into a single YAML file that uses Go templating.

Issue Fixed:

Fixes #3188.

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [jackfrancis]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Merging #3399 into master will increase coverage by 0.06%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##           master    #3399      +/-   ##
==========================================
+ Coverage   73.07%   73.14%   +0.06%     
==========================================
  Files         147      147              
  Lines       24945    24909      -36     
==========================================
- Hits        18229    18220       -9     
+ Misses       5588     5561      -27     
  Partials     1128     1128              

Impacted Files	Coverage Δ
pkg/engine/templates_generated.go	54.08% <77.77%> (+0.87%)	⬆️
pkg/engine/artifacts.go	99.12% <0.00%> (-0.88%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update edf8c6e...a2b122a. Read the comment docs.