Add all trigger fields to the documentation

### Describe your use-case which is not covered by existing documentation.

The current documentation lists only a subset of the fields that are available for scripted and declarative syntax `gitLab` triggers. Reading the code itself is necessary to determine what options are actually available.

Currently documented scripted:
```
branchFilterType: 'All',
triggerOnPush: true,
triggerOnMergeRequest: false,
triggerOpenMergeRequestOnPush: "never",
triggerOnNoteRequest: true,
noteRegex: "Jenkins please retry a build",
skipWorkInProgressMergeRequest: true,
secretToken: project_token,
ciSkip: false,
setBuildDescription: true,
addNoteOnMergeRequest: true,
addCiMessage: true,
addVoteOnMergeRequest: true,
acceptMergeRequestOnSuccess: false,
branchFilterType: "NameBasedFilter",
includeBranchesSpec: "release/qat",
excludeBranchesSpec: "",
```
Available, but missing from this list:
```
triggerOnBranchDeleteRequest: true,
triggerOnlyIfNewCommitsPushed: false,
triggerOnPipelineEvent: false,
triggerOnAcceptedMergeRequest: true,
triggerOnClosedMergeRequest: false,
triggerOnApprovedMergeRequest: false,
labelsThatForcesBuildIfAdded: "",
branchFilterName: "",
sourceBranchRegex: "",
targetBranchRegex: '^(.*/)?main$',
mergeRequestLabelFilterConfig: [
include: "",
exclude: ""],
pendingBuildName: "jenkins",
cancelPendingBuildsOnUpdate: true
```

Currently documented Declarative:
```
triggerOnPush: false,
triggerOnMergeRequest: true,
triggerOpenMergeRequestOnPush: "never",
triggerOnNoteRequest: true,
noteRegex: "Jenkins please retry a build",
skipWorkInProgressMergeRequest: true,
ciSkip: false,
setBuildDescription: true,
addNoteOnMergeRequest: true,
addCiMessage: true,
addVoteOnMergeRequest: true,
acceptMergeRequestOnSuccess: false,
branchFilterType: "NameBasedFilter",
includeBranchesSpec: "release/qat",
excludeBranchesSpec: "",
pendingBuildName: "Jenkins",
cancelPendingBuildsOnUpdate: false,
secretToken: "abcdefghijklmnopqrstuvwxyz0123456789ABCDEF"
```

Available, but missing from this list:
```
triggerToBranchDeleteRequest: false,
triggerOnlyIfNewCommitsPushed: false,
triggerOnPipelineEvent: false,
triggerOnAcceptedMergeRequest: true,
triggerOnClosedMergeRequest: false,
triggerOnApprovedMergeRequest: false,
labelsThatForcesBuildIfAdded: "",
branchFilterName: "",
sourceBranchRegex: "",
targetBranchRegex: '^(.*/)?main$',
mergeRequestLabelFilterConfig: [
include: "",
exclude: ""],
```

These are probably non-exhaustive lists, but they're what I was able to somewhat easily find when digging thru the code.

Might be good intro task for GSoC to familiarize with the structure, as loosely discussed https://github.com/jenkinsci/gitlab-plugin/issues/1005

### Reference any relevant documentation, other materials or issues/pull requests that can be used for inspiration.

_No response_