* Delete symlink to old Helm chart
* Update 'install' code to use common Helm template structs
* Remove obsolete TLS assets functions.

These are now handle by Helm functions inside the templates

* Read defaults from values.yaml and values-ha.yaml
* Ensure that webhooks TLS assets are retained during upgrade
* Fix a few bugs in the Helm templates (see bullet points):
* Merge the way the 'install' ha and non-ha options are handled into one function
* Honor the 'NoInitContainer' option in the components templates
* Control plane mTLS will not be disabled if identity context in the
config map is empty. The data plane mTLS will still be automatically disabled
if the context is nil.
* Resolve test failures from rebase with master
* Fix linter issues
* Set service account mount path read-only field
* Add TLS variables of the webhooks and tap to values.yaml

During upgrade, these secrets are preserved to ensure they remain synced
wih the CA bundle in the webhook configurations. These Helm variables are used
to override the defaults in the templates.

* Remove obsolete 'chart' folder
* Fix bugs in templates
* Handle missing webhooks and tap TLS assets during upgrade

When upgrading from an older version that don't have these secrets, fallback to let Helm
create them by creating an empty charts.TLS struct.

* Revert the selector labels of webhooks to be compatible with that in 2.4

In 2.4, the proxy injector and profile validator webhooks already have their selector labels defined.
Since these attributes are immutable, the recent change to these selectors introduced by the Helm chart work will cause upgrade to fail.

* Alejandro's feedback
* Siggy's feedback
* Removed redundant unexported custom types

Signed-off-by: Ivan Sim <ivan@buoyant.io>