feat: Add KO_GO_PATH env var

[embano1]

Makes go version used to build image binaries configurable via KO_GO_PATH. Optional, defaults to go resolved from $PATH.

Closes: #926
Signed-off-by: Michael Gasch 15986659+embano1@users.noreply.github.com

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[codecov-commenter]

Codecov Report

Merging #930 (e310747) into main (72e2752) will increase coverage by 1.20%.
The diff coverage is 78.57%.

@@            Coverage Diff             @@
##             main     #930      +/-   ##
==========================================
+ Coverage   51.21%   52.42%   +1.20%     
==========================================
  Files          44       43       -1     
  Lines        3419     3325      -94     
==========================================
- Hits         1751     1743       -8     
+ Misses       1439     1353      -86     
  Partials      229      229              

Impacted Files	Coverage Δ
pkg/commands/commands.go	61.53% <ø> (-2.75%)	⬇️
pkg/build/gobuild.go	57.07% <72.72%> (+0.10%)	⬆️
pkg/build/cache.go	41.66% <100.00%> (+0.82%)	⬆️

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[imjasonh]

Sorry for complicating this PR by including ko deps' removal in it. I've split that out into #937

[embano1]

Ah, let me wait until your PR is in and then rebase.

[embano1]

Ready after rebase @imjasonh