Increase log output readability

[HeavyWombat]

Changes

The current output of the Git step was using the log style of the controller,
which is configured to be machine consumable. However, the output should be
more aligned with the output that is created by other steps. Tools like Kaniko
or Buildpacks produce more human style output. This is also feedback that we
received from users, especially in the case when the source retrieval failed for
some reason, for example TYPO of the branch name or similar.

Replace ctxlog with log and simplify log output to be human friendly.

Add new end message that contains all relevant details, including HEAD info.

For reference:

• Before:

  {"level":"info","ts":1626871924.300413,"logger":"git","msg":"ssh","path":"/usr/bin/ssh","version":"OpenSSH_8.1p1, LibreSSL 2.7.3"}
  {"level":"info","ts":1626871924.319007,"logger":"git","msg":"git","path":"/usr/local/bin/git","version":"git version 2.32.0"}
  {"level":"info","ts":1626871924.3794508,"logger":"git","msg":"git-lfs","path":"/usr/local/bin/git-lfs","version":"git-lfs/2.13.3 (GitHub; darwin amd64; go 1.16.5)"}
  {"level":"debug","ts":1626871924.379594,"logger":"git","msg":"/usr/local/bin/git clone --quiet --no-tags --single-branch --depth 1 -- https://github.com/shipwright-io/sample-go /tmp/workspace/source"}
  {"level":"debug","ts":1626871925.524959,"logger":"git","msg":"/usr/local/bin/git -C /tmp/workspace/source submodule update --init --recursive --depth 1"}

• After:

  2021/07/21 14:39:15 Info: ssh (/usr/bin/ssh): OpenSSH_8.1p1, LibreSSL 2.7.3
  2021/07/21 14:39:15 Info: git (/usr/local/bin/git): git version 2.32.0
  2021/07/21 14:39:16 Info: git-lfs (/usr/local/bin/git-lfs): git-lfs/2.13.3 (GitHub; darwin amd64; go 1.16.5)
  2021/07/21 14:39:16 /usr/local/bin/git clone --quiet --no-tags --single-branch --depth 1 -- https://github.com/shipwright-io/sample-go /tmp/workspace/source
  2021/07/21 14:39:16 /usr/local/bin/git -C /tmp/workspace/source submodule update --init --recursive --depth 1
  2021/07/21 14:39:17 Successfully loaded https://github.com/shipwright-io/sample-go (ref: refs/heads/main) into /tmp/workspace/source
  

Submitter Checklist

• Includes tests if functionality changed/was added
• Includes docs if changes are user-facing
• Set a kind label on this PR
• Release notes block has been filled in, or marked NONE

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Release Notes

Improved output messages created by the Git step to be more human readable.

[SaschaSchwarze0]

Hi @HeavyWombat, you just requested a review from me. Please be aware that I am on vacation and come back July 26th.

[SaschaSchwarze0]

/lgtm
/approve

[openshift-ci]

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