Use proper namespace for PHP translation

[maxime-rainville]

We made the module localisable in #113

However we don't appear to be using our regular convention for PHP translation key.

e.g.:

This line

silverstripe-linkfield/src/Models/Link.php

Line 106 in 7f65d4f

_t('LinkField.LINK_TYPE_TITLE', 'Link Type'),

should be written

_t(__CLASS__ . '.LINK_TYPE_TITLE', 'Link Type'),
// OR
_t(Link::class . '.LINK_TYPE_TITLE', 'Link Type'),

Acceptance criteria

• All PHP translation keys use the standard approach used in other module.

PR

• MNT Use FQCN for PHP translations #164

[GuySartorelli]

@emteknetnz Can you please link to any relevant PRs in the description?

[GuySartorelli]

PR merged