Cache statuses/types/severities/projects

[FletcherAU]

• [x] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/slack_home.py#L517-L525
• [ ] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/slack_forms.py#L215-L222
• [ ] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/slack_forms.py#L523-L535
• [ ] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/slack_forms.py#L537-L549
• [ ] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/slack_home.py#L288-L296
• [ ] https://github.com/Perth-Artifactory/taiga_sync/blob/ecaec07eeaa06df9865f5399f7c3e9f80672ed72/util/taigalink.py#L793-L798

[FletcherAU]

This should shave ~100ms off of a 1000ms block generation