flags: added "RESTICPROFILE_{FLAGNAME}" env vars

[jkellerer]

Implements #334

State:

• [x] implementation and tests
• [x] documentation
• [x] cleanup

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 69.96%. Comparing base (71ce2d0) to head (c64fb47).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #335 +/- ## ========================================== + Coverage 69.88% 69.96% +0.08% ========================================== Files 118 118 Lines 11891 11923 +32 ========================================== + Hits 8309 8341 +32 Misses 3193 3193 Partials 389 389 ``` | [Flag](https://app.codecov.io/gh/creativeprojects/resticprofile/pull/335/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Fred) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/creativeprojects/resticprofile/pull/335/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Fred) | `69.96% <100.00%> (+0.08%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Fred#carryforward-flags-in-the-pull-request-comment) to find out more.

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[jkellerer]

Doc links are fixed in #323. The PR is ready for review.

[creativeprojects]

Doc links are fixed

Yes, they must have noticed they messed up their links and put them back 😆