fix: add saml application

[stebenz]

SAML applications can be managed with ZITADEL's terraform provider

Definition of Ready

• [ ] Short description of the feature/issue is added in the pr description
• [ ] PR is linked to the corresponding user story
• [ ] Acceptance criteria are met
• [ ] All open todos and follow ups are defined in a new ticket and justified
• [ ] Deviations from the acceptance criteria and design are agreed with the PO and documented.
• [ ] No debug or dead code
• [ ] My code has no repetitions
• [ ] All non-functional requirements are met
• [ ] The generic lifecycle acceptance test passes for affected resources.
• [ ] Examples are up-to-date and meaningful. The provider version is incremented.
• [ ] Docs are generated.
• [ ] Code is generated where possible.

[codecov[bot]]

Codecov Report

Attention: 69 lines in your changes are missing coverage. Please review.

Comparison is base (a1c0eaa) 63.20% compared to head (720e986) 63.32%. Report is 1 commits behind head on main.

:exclamation: Current head 720e986 differs from pull request most recent head 49fb09f. Consider uploading reports for the commit 49fb09f to get more accurate results

Files	Patch %	Lines
zitadel/application_saml/funcs.go	53.90%	46 Missing and 19 partials :warning:
zitadel/application_api/funcs.go	0.00%	1 Missing and 1 partial :warning:
zitadel/application_oidc/funcs.go	0.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #154 +/- ## ========================================== + Coverage 63.20% 63.32% +0.12% ========================================== Files 156 159 +3 Lines 12609 12840 +231 ========================================== + Hits 7969 8131 +162 - Misses 3379 3427 +48 - Partials 1261 1282 +21 ``` | [Flag](https://app.codecov.io/gh/zitadel/terraform-provider-zitadel/pull/154/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zitadel) | Coverage Δ | | |---|---|---| | [acceptance-tests](https://app.codecov.io/gh/zitadel/terraform-provider-zitadel/pull/154/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zitadel) | `63.32% <70.63%> (+0.12%)` | :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=zitadel#carryforward-flags-in-the-pull-request-comment) to find out more.

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