Attempt to provide more helpful error message when git URL may be misspelled

[yorinasub17]

Description

Attempts to fix https://github.com/gruntwork-io/boilerplate/issues/120

Since it's impossible to catch all misspelled URL formats, this is a best effort attempt to catch the most common misspelling of using git@github.com/ORG/REPO instead of git@github.com:ORG/REPO.

TODOs

Read the Gruntwork contribution guidelines.

• [x] Update the docs.
• [ ] Run the relevant tests successfully, including pre-commit checks.
• [x] Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• [x] Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes (draft)

• Updated error handling to output a more helpful error message if the template URL may include a typo for a Git URL.

[yorinasub17]

Sample error message output from test:

[boilerplate] 2022/08/08 14:33:33 Loading boilerplate config from ../test-fixtures/regression-test/misspelled-git/boilerplate.yml
[boilerplate] 2022/08/08 14:33:33 Loading boilerplate config from ../test-fixtures/regression-test/misspelled-git/boilerplate.yml
[boilerplate] 2022/08/08 14:33:33 Processing dependency guestbook, with template folder ../test-fixtures/regression-test/misspelled-git/git@github.com/JDoe/guestbook.git/nginx?ref=v0.1.0 and output folder /var/folders/36/ljcx66pj73zd3sq1r1tsr_300000gn/T/boilerplate-test-output1090859506/guestbook
[boilerplate] 2022/08/08 14:33:33 Loading boilerplate config from ../test-fixtures/regression-test/misspelled-git/boilerplate.yml
ERROR: Could not find boilerplate.yml in ../test-fixtures/regression-test/misspelled-git/git@github.com/JDoe/guestbook.git/nginx?ref=v0.1.0/boilerplate.yml and the missing-config-action flag is set to exit. Template URL looks like a git repo. Did you misspell the URL? Should be one of the following: git::`ssh://git@github.com/ORG/Repo`, `github.com/ORG/Repo`, or `git@github.com:ORG/Repo`.